Meaning of “DecoPin(でこぴん)”

“DecoPin(でこぴん)” means tapping the other person’s forehead firmly with your finger.
Deco(でこ) means forhead and pin(ぴん) is a onomatopoeia that represents the sound of tapping I think.

“DecoPin(でこぴん)” has an image of being a punishment game between close friends, in my image.

Also, “DecoPin(でこぴん)” is a name of Shohei Ohtani’s dog!

Example Conversation

A: Which side are you betting on?
B: Hmm, I’ll bet on the side where team C wins.
A: Alright, I’ll bet on team D then. If I lose, “DecoPin(でこぴん)”!

A: どっちに賭ける？
B: えー、じゃあteam Cが勝つ方に賭けるかな
A: じゃあ俺は team Dに賭ける、外したらデコピンね！