I dreamt I was playing Pokémon Trading Card Game Pocket and I got a "Boo!"

In the dream I was playing Sleep Scam (Milotic EX edition) on my alt and got a big win streak. I went back to the gifts section to collect thanks and shop tickets from wins and some cards I shared and I was surprised to see in lieu of a Shop Ticket, one of my prior opponents had given me a "Boo!" It was just this icon with a message that said "You Got A Boo!"

I checked the updates (as I had just clicked one away without reading it when I opened the game) and sure enough there was a message that explained it.

They added a new feature where instead of a Thanks, you could give other players a Boo! Each player could only give one Boo a day (so I guess you were encouraged to save it for someone that really pissed you off). A Boo subtracts one Shop Ticket from your total and you could lose up to three Shop Tickets a day from Boos.