Some people live to create hell for others.
Every gathering is an opportunity to throw in a slight, stir the spot, or manipulate others into some elaborate mess.
Or in some cases, these big a**hole moves are purely self-involved and reflexive, with no major plan for destruction, just a tunnel vision mentality.
The biggest d*ck move I have ever witnessed was at my friend's birthday party (around 10 years old). His grandmother sent 10 $1 scratchies in the mail.
The dick move being that she checked all the scratchies before sending them in case one had a big payout. I got to see his face drop as he opened the envelope to find 10 pre-scratched, worthless scratchies.
My good buddy's wife is famous for her lack of tact and general pissiness. Their little girl is about 2 years older than mine. Her birthday was coming up, and my daughter (7 at the time) wanted to pick out the birthday gift.