General expressions:
* La tante drôle: This is the most literal translation, but it sounds a bit formal.
* La tante rigolote: This is a more informal and friendly way to say "funny aunt".
* La tante qui fait rire: This means "the aunt who makes you laugh".
More specific expressions:
* La tante qui a toujours une blague à raconter: This means "the aunt who always has a joke to tell".
* La tante qui est toujours de bonne humeur: This means "the aunt who is always in a good mood".
* La tante qui sait comment faire rire les enfants: This means "the aunt who knows how to make the children laugh".
You can also use the aunt's name and a descriptive adjective:
* Monique, la tante amusante: This means "Monique, the funny aunt".
The best option depends on the context and the level of formality you want to convey.