One time Chester Bennington from Linkin Park shook my hand in the middle of a song.
Also, in 2009 during Lady Gaga's first major US tour, my dad ran into her at a Dunkin Donuts at 5 am. He had no idea who she was, and said "good luck at your show tonight" with a hint of sarcasm. Needless to say, I put him in his place about who he had actually met. My exact words, I think, were "come on dad, she's the one who wore the meat suit!!!"