Kristin Cavallari put Jay Cutler on the hot seat -- asking him straight up ... now that you're not playing football, what exactly do you DO all day long?!
It's all part of their new E! reality show, "Very Cavallari" -- which follows KC as a working mom and Jay Cutler ... as a non-working mom.
No, really ... Cutler even jokes about how his life revolves around picking up their kids from school and beating "all the other moms there."
At one point, Kristin turns to Jay and says, "Like honestly, what do you do all day?