[ Oh right, they're supposed to be having a challenge. And Kakashi can hear Gai coming from a mile away. So to speak. So he gets up in a tree to conceal himself and waits for Gai to more or less... catch up, so he can drop down behind him and potentially make Gai scream like a little girl.

...Hmm.

Okay, actually that almost sounds like it might be a little amusing. Assuming Kakashi manages to get the proper reaction. ]