What's the most fun a girl can have without taking her clothes off?

Depends on the girl.
A walk in the woods, drinks with friends, shopping with someone's else's plastic, .....

Having a guy take her clothes off

Talking about taking her clothes off.

The same fun as taking your clothes off, depending what your wearing, they can stay on

I was going to say shopping but trying on clothes would also involve taking clothes off

Skydiving was pretty fun and you add another layer of clothing for that.