I'm learning english and I have problem with translation name of sound: "Tell Me When We're Having Fun". I not understand why was Present Continuous form of tense used? Is it not should use Present Simple (exactly "have fun"), as used definition in a general sense (have fun) or it means that action takes place right now and this form emphasize it here?
(This question would be better on the English Language Learners site)
It depends on the kind of condition.
If it is a punctual condition, then we use the simple present:
Tell me when you get here.
But here the condition is that something is happening and continuing to happen at that time:
Tell me when we're having fun.