'Course We had a slight difference in preparation at the partys I remember doing this. You need a round melon (water', cantaloupe, honeydew, etc.), some kind of stand or brace to put the melon on, booze and ice. If you can remove seeds without disturbing the flesh too much, do it. Cut the melon in half and put it in a cavity-up position. Fill the cavity with rum or vodka or any favorite mixable liquor and ice. Prepare it at least an hour ahead of time, 3-5 hours is better (gives the booze a chance to invade the meat of the melon, poking holes helps) and keep it cold. Put a spoon out with (small) glasses and let people serve themselves with as much or as little melon mixed into the drink as they want.
If you ask nice I can give my recipe for any number of appetizers. <grin>