Graduating students at USC got a special send-off on Friday, May 12 from commencement speaker Will Ferrell: a heartfelt (if slightly off-key) rendition of Whitney Houston's epic ballad, "I Will Always Love You."

The actor and former Saturday Night Live star belted out the song as a conclusion to a 25-minute inspirational speech about his journey to stardom and his early struggles as a comedian. But while being serenaded by Ferrell might have been a surprise to those in the audience, it's actually just the latest in a series of epic musical moments that have defined his career. Below, we've rounded up a few of the best (worst) times when he's burst into song.

1. The Second Coming of Robert Goulet

Will Ferrell's impression of the French-Canadian crooner is one of his standbys, and though he's never said so outright, it certainly seems like his favorite — considering that "Goulet" sometimes shows up in Ferrell's place during latenight engagements.

2. A deal with the Devil.

Ferrell's happy-go-lucky song about a guy named Fred and his pair of slacks might not have been good enough to impress Garth Brooks, but we'll take it. Ooooh, Fred's got slacks!

3. Marty Culp, superstar.

Nobody sings today's hottest hip-hop hits like perennial favorites Marty and Bobbi Culp, seen here getting ready to belt their way through "I'm Sexy and I Know It".

4. He's got his tight pants on.

Clearly, Will Ferrell wasn't about to pass up the chance to don a pair of crotch-hugging white slacks and sing about it with Christina Aguilera on national television.

5. And of course, more cowbell.

It's not a song, per se, but no roundup of Ferrell's musical moments would be complete without this scene from his brief, passionate career as a percussionist.