Her co-stars got her to belt out 'Believe' Conan O'Brien's show, and it was wonderful.
And this isn't J-Law's first time letting it all out on Conan - back in 2013 she revealed a pretty hilarious sex toy story which left her red faced.
Jennifer said she hid a stash of sex toys under her hotel bed, after being given them by a friend as "a joke", only for them to be found by the hotel maid.
The maid then proceeded to neatly arrange them for the 23-year-old on her bedside table. Awks. Watch her tell the whole story here.