Use 'act the fool' in casual settings, not formal ones where serious behavior is expected.

Correct Occasion

'Act the fool' isn't normally used to insult someone, but to describe playful behavior.

Not Insulting

It often implies someone is willingly being silly to entertain others without feeling embarrassed.

Can imply someone pretends to not understand something to avoid responsibility or work.

Sometimes used to show someone is more clever or aware than they are pretending to be.

Be careful using 'play the fool'; others might think you really lack understanding.