Jimmy Fallon has established a brand for "The Tonight Show" that pulls in young viewers, doesn't alienate old viewers, and churns out excellent viral content. He's evolved from the guy who giggled his way through "Weekend Update" to the most trusted name in late-night raucousness. Not a bad arc, everyone. 

For his 40th birthday tonight, we're celebrating Jimmy's 10 coolest and funniest career moments. They range from the musical to the absurd, and all ten feature some version of hilarity that only he can deliver.