Something I always thought would be interesting, even if not as a gag but a special event maybe, would be have a REAL, full realism day, or event.
It you run into one of your countrymen's planes, taking off or landing, you both get wrecked like you would in the real world. Run into ANY plane up in the air and you both get wrecked.
The flack over your field is just as deadly to you as the flack over enemy fields.
We have a little bit of it now with rounds bouncing off friendly planes and coming right back into your plane, but make it so any hit on any plane creates the same damage, friendly or not.
In other words, make the game just like the real world. Think of what a bloodbath that would be. I imagine it would all some of us could do just to get the plane off the ground with a game like that, at least until we got used to it.