John William Ferrell, so first day of school, I'd be John. The teacher would be like 'John Ferrell?' and it was so embarrassing to me to have to say, 'Here, but I go by Will, I don't go by John.' ...

Gareth Cattermole/Getty Will Ferrell’s son Magnus has seen his share of wild dinner guests. According to Magnus, 20, his dad’s friend John C. Reilly once treated a party to a sweet serenade.