Kristin Cavallari to Jay Cutler: What The Hell Do You Do All Day?!

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?"

Kristin also lectures Jay about it's time for her career as a jewelry designer to get priority -- saying, "You have to realize how many sacrifices I've had to make over 8 football seasons that we've been together."

For the record, Jay's 12-year NFL career earned more than $120 MILLION for their family.