Think of your favorite frat boy. Now think of Ashton Kutcher. Who would have knew that some of these well known male celebrities were once frat boys back in their college days? I mean everyone does have a past, so aren't you curious to know what type of frat boy these celebs were or how they looked like?

Well, here are 12 male celebrities that you probably had no clue that they once belonged to a frat.

1. Ashton Kutcher: Delta Chi, The University of Iowa

Ashton, um, could you please re-enroll in college? Please and thank you!

2. Dave Franco: Phi Kappa Psi, USC

No wonder his character, Pete, from Neighbors fit him so perfectly.

3. Brad Pitt: Sigma Chi, Mizzou

Lovin' those short shorts, Brad.

4. Matthew McConaughey: Delta Tau Delta, The University of Texas at Austin

Matthew was defiantly the hottest brother that every girl wanted to hook-up with.

5. Eli Manning: Sigma Nu, Ole Miss

Really...?

6. Luke Bryan: Sigma Chi, Georgia Southern University

Probably had tons of country girls shaking it for him.

7. Will Ferrell: Delta Tau Delta, USC

Let's just say that nothing has changed.

8. Adam Sandler: Tau Epsilon Phi, NYU

Who else is just as curious to find out which type of brother Adam Sandler was?

9. Ty Burrell: Sigma Chi, University of Oregon

Nope, sadly, he isn't a current frat boy at your college. Talk about a formal date.

10. Paul Rudd: Sigma Nu, The University of Kansas

Yup, who now feels a little bit Clueless...

11. David Schwimmer: Delta Tau Delta, Northwestern University

Tell me about your glory frat days and let's become best F.R.I.E.N.D.S, Dave!

12. Zac Efron: Delta Psi Beta

Well... kind of...?