noun
long ears; gossiper
Literally 'rabbit ears'. Idiomatically refers to a person who has sharp hearing for gossip or secrets, akin to 'having big ears' in English.
彼は兎耳だから、内緒話は気をつけて。
He's a gossiper, so be careful with secrets.
あの人は兎耳で、すぐ噂を広める。
That person has big ears and spreads rumors quickly.