It's when a Generation X population member behaves likeones 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.
The act of fingering a girl whilst eating a formal dinner with friends or family or important people.
"Stop that Jack, don't gilinsky me right now." She quietly moaned.
"But you're enjoying it." He replied.
"But we're eating dinner with my parents." She replied.
"OK but we'll continue this later." He smirked.