With a mere flick of her thumb, Jennifer Lopez saved what could have been an embarrassing, moment-ruining situation when Adele accepted one of her Grammy awards. It seems that a notorious celeb prankster/harasser was looking for another 15 seconds of fame. 

Adele was walking onstage to accept her golden gramophone for Best Pop Solo Performance when Ukrainian TV presenter Vitalli Sediuk approached. He told her, "It's such an honor to win this award! I love you Adele!"

He was about to join the confused chanteuse onstage when Lopez communicated something to him with one mere gesture, and he exited upstage. (Lopez completely kept her cool, even as she looked over her shoulder to make sure he was gone.)

Sediuk is the same guy who got slapped by Will Smith when he tried to smooch the star at the 'Men in Black 3' premiere -- a repeat offender in terms of celeb harassment disguised as pranks.

Here's where it gets scary: the awards had heightened security because of the Christopher Dorner manhunt and this guy still got in without tickets or any sort of clearance. Sources said he just strolled in alongside Katy Perry, who apparently inadvertently distracted everyone with her rack.

Once he got into the arena, he plopped himself down in the second row behind Justin Timberlake. It turns out Adam Levine was actually supposed to take that seat, but he came late and just sat elsewhere instead of being a pain in the ass about it -- the one time it would have paid off.

Once Sediuk got offstage, he was finally apprehended (and noticed) by Grammys security and arrested, spending the night in jail.