Use 'go bananas' when someone is showing very high levels of excitement, often unexpectedly.

Extreme Excitement

'Go bananas' is used in casual conversation, not in formal settings.

Informal Speech

It often has a positive connotation, like when describing joy at a party or event.

Use 'go bananas' when someone becomes very angry suddenly or unexpectedly.

Typically used among friends or in informal situations, not in professional or formal settings.

It's often associated with a negative reaction or anger, unlike its positive excitement use.