This is no big deal to make, and it's as impressive as baked Alaska. Cut two large pink grapefruit in half and remove the fruit. Drain off the grapefruit juice and use it for something else or drink it. Cover the grapefruit sections with 1/4 cup rum and let it sit in the refrigerator until you're ready for dessert.
Scoop the membranes out of the grapefruit shells. Be careful not to poke holes in the shells. Just before serving, put the rummy grapefruit sections back in the shells and cover each with a scoop of vanilla ice cream. Top with meringue, sealing the edges of the shells and ice cream. Brown lightly under broiler and serve immediately. Makes 4, but of course you can make as many as you want.