笑わざるを得なかった

couldn't help laughing

→ 笑う
phrase Rare #28,258
couldn't help laughing A formal expression meaning that someone had no choice but to laugh. The pattern ~ざるを得ない means “cannot avoid doing.”
JA: その映画はあまりに面白くて、笑わざるを得なかった。
EN: The movie was so funny that I couldn't help laughing.

私達は彼の話を聞いて笑わざるを得なかった

We couldn't help laughing when we heard him talk.

私は彼を笑わざるを得なかった

I couldn't help laughing at him.

その冗談には笑わざるを得なかった

I couldn't help laughing at that joke.

その光景を見て笑わざるを得なかった

I couldn't help laughing when I saw the scene.

その光景に僕は笑わざるを得なかった

I couldn't help laughing at the sight.

彼の話はあまりにおかしかったのでみな笑わざるを得なかった

His story was so funny that everyone couldn't help but laugh.

私はその計画を笑わざるを得なかった

I couldn't help but laugh at that plan.