Fun e

It just means funny

Person1: your fun e
Person2 no I’m funny
Person1: that’s what I said

fun-e

When somethings so funny you want people to know it's funny while sounding cool.

Also could be uses as: "Fun with a pinch of e" or "Fun with a dash of e"

Me: Did you see that new own3donline.com episode?
You: Ya, it was fun-e

FUN e

Really not funny at all, used to shut someone down when they make a stupid joke.

Guy: and so then i was like "daaaaaamn"
Gurl: FUN e

E-Fun

it means to have fun online but in a broader sense, and usually used in discord chats as a way to call others to play.

Let's have some E-Fun on that new game.