We ask the two actresses a few questions about their new movie ''Tammy''

By Adam Markovitz
Updated April 11, 2014 at 04:00 AM EDT

You two seem so natural playing grandmother and granddaughter in Tammy. Did you do any bonding before the shoot?
Melissa McCarthy We did tons of trust exercises. Pushing Susan down — but then catching her. [Laughs]

Susan Sarandon I just took her children for a few days to see if she trusted me. [Laughs]

McCarthy No, we had martinis. Does that count?

Absolutely. You spend a lot of time in the movie in a car together. What was that like?
McCarthy You get punchy and forget that there are microphones on you. You start telling a really inappropriate story — like, “This one time, in college…” — and then you’re like, “Wait, there are a hundred people listening with headsets on.”

Have either of you ever been on a road trip like this?
Sarandon I went up the [Pacific] coast with my daughter when she was in eighth grade on a road trip to join Tim [Robbins] and the boys in Seattle. It was right at the height of her romance with the musical Rent — and that’s the only music we had on the entire trip.

McCarthy After this movie wrapped, Ben [Falcone] and I took the kids and drove from Niagara Falls back to Los Angeles. That was a doozy. Here’s a tip: Don’t do that with a 6-year-old and a 3-year-old. We thought it would be great, and then we’re like, “Oh my God.”

Sarandon Next year, when they’re 7 and 4, you should put them in charge of the finances as you drive across.

McCarthy No, I’ll say, “See you on the other side! I’m taking a plane. Susan and I are busy listening to Rent.”