When Jimmy Fallon took over The Tonight Show we expected, if anything, an increase in professionalism. You don’t want to mess up things when moms and dads are watching. Good thing Fallon, et al, know the joy of a train wreck. Last night, Fallon had his former “Weekend Update” co-anchor Tina Fey on and they tried to a bit called “Lip Flip,” in which their lips were superimposed onto the other’s. It instantly, and for its entire five minutes, goes hilariously wrong, to the point that Fey just starts uncontrollably giggling. At the end, they try to sing a duet of “Endless Love.” Though it sounds terrible, it does reflect how we feel about these two.