We can’t remember a time when we didn’t spend our lunchbreaks sharing quirky, funny or incredibly cute video clips with our friends. Since YouTube’s launch in 2005, hundreds of videos have become viral sensations, watched and discussed by millions worldwide. Some spend a few weeks in the spotlight and fade into internet obscurity, but a select few go on to become a cultural phenomenon - with CDs, books and careers made from uploading one clip. Much of YouTube’s output has now become slicker than ever thanks to marketing companies, but sometimes, you just can’t beat a shakily filmed clip of a cute creature. So, if you’ve got a few minutes to spare, take a look at our selection of the best viral videos of all time. From the hilarious to the bizarre, here they are in no particular order…

1. Scary Mary Poppins

Many of you may remember settling down to watch Mary Poppins as a kid. This cleverly edited film trailer shows what would happen if Disney decided to make a horror film, and Poppins went over the dark side. It makes “a spoonful of sugar” sound awfully sinister.

2. Teenage Dream

15 year-old Keenan Cahill is a serious Katy Perry fan. His lip-synching talents led to him performing with Katy Perry in a video, and celebrities such as 50 cent and Tine Tempah now request to star on his Youtube channel.

3. Susan Boyle, I Dreamed a Dream

One of the biggest viral phenomenon of 2009, Susan Boyle’s plain appearance and powerful voice wowed audiences in the auditions of Britain’s Got Talent, and worldwide as news of the video spread.

4. Dramatic Chipmunk

It may only be five seconds long, but this clip of a shocked chipmunk still makes us chuckle.

4. Talking Twin Babies

Baby talk, in its purest and most hilarious form.

5. The Keyboard Cat

Because a video of a cat doing something silly is guaranteed internet gold. Here Fatso the cat shows off his keyboard skills.

6. Leave Britney Alone!

When Britney Spears suffered a meltdown in 2007, uber-fan Chris Crocker uploaded this emotional video defending his idol. It recieved 2 million views in 24 hours, and spawned a spoof video by actor Seth Green.

7. Rick Roll'd

In case you've never been "Rick Roll'd", the 2007 craze involved tricking users into clicking a link to the music video for Rick Astley's 1987 hit Never Gonna Give You Up. Rickrolling really hit the mainstream when even Fox News got in on the act, as this video of an news anchor getting Rick Roll'd shows.

8. Chocolate Rain

Tay Zonday’s dulcet tones and songwriting skills helped make Chocolate Rain a viral sensation. With 70 million views plus on Youtube, Tay went from being a grad student to a fully fledged singer, and even appeared on Lily Allen's short-lived TV show, covering her hit Smile.

9. Dancing Baby

One of the very first viral video hits in 1997, this video of a (slightly creepy) dancing baby even featured on Ally McBeal .

10. Boo

We love a good animal video at Stylist, but few have as high a cute factor as this clip of fluffy pup Boo. Boo has his own blog, facebook page, and a book coming out later this year too.

11. Condo-licious

Seen Black Eyed Pea Fergie's Fergalicious video? Here's what would happen if ex-secretary of State Condoleeza Rice made her own version. She sure can rap...

12. D*** in a Box

Saturday Night Live has a long history of producing Youtube hits, from Natalie Portman rapping to this spoof music video, featuring Justin Timberlake and Andy Samberg posing as nineties-style crooners. Comedian Samberg and his friends Kiv and Jorm form comedy troupe The Lonely Island, who have now had two albums worth of similar spoof videos, featuring Lady Gaga, Rihanna, and er, Michael Bolton.

13. Ninja Cat

This stealthy cat demonstrates all the skills of a ninja on camera.

14. Take on me (literal version)

The first clip to kick off the "Literal Video" craze (where the original video lyrics are replaced with someone singing exactly what happens in the video), we could never look at A-Ha the same way again after seeing this.

15. Will it blend?

Here's a genuinely funny viral marketing campaign - in which Tom Dickson, founder of the Blendtec line of blenders, shows how his product can literally blend anything - from iPhones, to Justin Bieber.

16. Charlie bit my finger, again!

This video of cute warring siblings became one of Youtube's biggest ever hits, and currently has around 361,316,907 views.

17. Speak the Hungarian Rapper

Tamás Deák is known as rap artist, model and actor 'Speak' in his home country of Hungary. On the internet, he is known for the unintentionally hilarious video for his 2003 single Stop the War. Featuring cameos from various Hungarian singers, Speak references Tupac and Biggie before unleashing a grey pigeon into the sky.

18. Obama Girl

This music video from Barely Political was released at in the midst of the primary US election campaign. The video racked up 14 million views and made a star of Amber Lee Ettinger, the girl with the hots for the President.

19. Surprised Kitty

Ok, this is the final cute animal video on our list. This adorable kitten is easy to shock - and very good at acting suprised.

20. Hitler reacts to the modern world

Part of a series of hilarious subtitled clips from the movie Downfall, this video shows how Hitler might have reacted had he witnessed Kanye West's outburst at the VMA's in 2009. Clue: he didn't take it well.

Have we missed your favourite viral off our list? Share your ultimate YouTube hit in the comments below.