Before the gig, get some chicken/Lamb, cut it into cubes, marinate it in lemon juice, salt and pepper. Leave it in the fridge. After gig, skewer the meat and grill/broil/whatever. Good with pitta bread, salad and hummus/chili sauce.
5 mins of prep that afternoon make a great meal later on that night.
Edit: obviously I wait til I get home
How cool would it be if you could grill (and eat) a couple of marinated lamb skewers during a gig?
I usually end up watching sports on the bar TVs after most of the people have left, but grilling would be awesome!