Ashton Kutcher takes over the monologue on Lopez Tonight, and Demi's dude certainly doesn't hold back when ripping on Heidi Montag!

As for Ashton's performance, let's just say George shouldn't be worried that his job is in jeopardy.

Maybe he was just worn out from his day of shooting his the set of his rom-com Friends With Benefits in LA, with rapper-turned-actor Ludacris:

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In the film, Kutcher stars with Natalie Portman as friends whose "no strings attached" relationship is threatened when they start to develop romantic feelings for each other.

Looking very boyish in baggy jeans and an oversized sweater, it's hard to believe that this "man" is married to a 47-year-old! A HOT 47-year-old, but still!