It was hilarious, unexpected and totally overshadowed Ryan Gosling's big moment -- since the smooch happened right behind his head as he was about to accept his award.
Here's a refresher.
Well now, Andrew has taken the time to explain exactly what happened.
Apparently, Andrew and Ryan Reynolds were planning on kissing if Ryan won for "Deadpool." The plan was for Ryan to go toward wife Blake Lively for a kiss, and then swerve at the last moment toward Andrew.
But, when Ryan Reynolds lost to Ryan Gosling, the duo decided to go for the kiss anyway -- LOL.