It doesn't necessarily eject hot air outside, right? It just "ejects" heat outside. It could easily have two tubes or something, sucking in warm air from the ou

It doesn't necessarily eject hot air outside, right? It just "ejects" heat outside. It could easily have two tubes or something, sucking in warm air from the outside, heating it up, and ejecting it outside again. However, since you have to create a (temporary) opening to put part of the mobile ac outside, warm air will still get in. You could just use a fan to blow air over water onto your body. The evaporation will cool it down a little.