Robert Pattinson and Kristen Stewart prepare to win the Best Kiss award at the MTV Movie Awards tonight.The 'Twilight' stars have won the award the last two years, but their acceptance smooches were duds. The first year, it was a pretend kiss, and the second, it was a hidden peck.Last year, they reportedly stayed up all night trying to decide what to do should they win Best Kiss."They were having a great time deciding what they were going to do. "They don't take it very seriously, some of their ideas were just hilarious — Rob thought it was all really funny."This year will be different as the couple have been rehearsing the big moment.Kristen Stewart shares another Best Kiss nomination with fellow Twilighter Taylor Lautner.'Twilight Saga: Eclipse" leads the nominations, with eight nods, including Kristen Stewart for Best Female Performance and Robert Pattinson and Taylor Lautner competing for Best Male Performance.'Inception' and 'Harry Potter and the Deathly Hallows Part 1' are close behind with seven and six nominations, respectively.The awards are being held at the Gibson Amphitheatre in Universal City, CA, and will be hosted by Jason Sudeikis of "Saturday Night Live."