Japanese by Example
Learning through examples in manga

Worth teasing with 〜甲斐がある

からかい上手の高木さん » Volume 2 » Page 141

Takagi teases Nishikata, causing him to jump up from his chair and get scolded by the teacher. After sitting back down, Nishikata demands to know why Takagi is laughing for.

高木(たかぎ):
西片(にしかた)ってホントからかい甲斐(がい)があるねぇ。」
"Teasing you really is worth it."