It's when a Generation X population member behaves like ones of the Millennial generation.
David had a meltdown and felt entitled to help over a problem he was having, for a 40-year-old mature man he surely exhibited some GillennialX behavior.
A sweet Dutch man with glorious long locks of hair who is extremely considerate. He is a great listener and has great input. A Gilles can pull you out of a bad day at any time, his smile is extremely contagious. He also likes to make jokes with vampire references. He is very intelligent, not to mention extremely attractive. If you ever meet a Gilles, keep him safely by your side, he will treat and human being with the upmost respect.
The Dizzy Gillespie is when a man is giving oral sex to a woman who farts. The rank fart rolls upward into his mouth distending his cheeks like he's blowing into a trumpet. Thus making him look like Dizzy Gillespie.
My best friend fell out when I told her my husband was pissed at me because after date night I was gassy and drunk and gave him The Dizzy Gillespie during his late night dessert.