William H. Macy has had to do a lot of outlandish and atrocious things as Frank Gallagher on Shameless, fromperforming favors in a bathroom for beer money to selling his kids to child services out of spite.

The spectrum of his lewd activities is very wide, but the veteran actor has one particular Frank encounter that stands out to him as the most insane. "Joan Cusack had put a lot of things up Frank's butt over the seasons, but [the script] said her foot," he tells TVGuide.com. "First of all, I don't think that's possible. Secondly, she wiggles her toes and I like it?"

The depravity doesn't end with Sheila's (Cusack) proclivity for butt stuff. Frank is up to more jaw dropping stunts in Season 6 too. "This season started off with me on the grave having sex with my dead girlfriend's grave," he says. "It's been the constant thing of figuring out where is the reality in this? Is this funny? Can I make it funny?"

Can he? Find out by tuning in to Shameless Sundays at 9/8c on Showtime.

(Full disclosure: TVGuide.com is owned by CBS, one of Showtime's parent companies)