Zac Efron appeared on Conan last night, and while he doesn't talk about the infamous red carpet condom incident, he did reveal some secrets from his past. Zac is a self-professed "nerd" who was obsessed with musical theater as a kid, and he admits that he hasn't always been great with the ladies!

The 24-year-old actor also performed a live a cappella version of the Beach Boys' hit “Barbara Ann,” with Conan -- check out the video above!