boomerang
Refers to the curved throwing tool that returns to the thrower, or metaphorically to something that comes back to the originator.
I bought a boomerang as a souvenir from Australia.
His criticism came back to him like a boomerang.
The kids were playing in the park, throwing a boomerang.
I saw someone wearing swim briefs at the beach during summer vacation.
His criticism ended up backfiring on himself.