Im sure most of you out there have had something called "jungle juice" which usually involves lots of fruit, some everclear and a clean trashcan/bucket. The fruit absorbs a lot of the alcohol so you could get dangerously drunk just by eating the fruit. This instructable shows how to make watermelRum, or watermelon that absorbs rum. Very simple.
Cut a plug out of the watermelon. The melon should sound hollow when you knock on it. After you cut that out, put it upside-down in a big bowl and let the juice drain for at least a few hours. You may stick a knife up the hole and cut around to get more juices to come out. I also used a wooden spoon to press on the sides of the whole to squeeze more juice out of the watermelon sponge.
When you think no more juice will come out, fill er back up with your favorite alcohol. I chose clear Rico Bay rum, because its cheap, its clear, and tastes ok. Not great, just ok. You can also use vodka, everclear (careful with that one) and I kinda doubt gin would taste good. I filled mine back up almost all the way with rum, then put the plug in and let it sit in the fridge for some more hours. I think I could only wait about 5 hours, and by then the rum made parts of the watermelon have darker red spots than the rest. Those were the parts where the alcohol was chillin. For more potency, I suppose you just either let it drain/dehydrate more, let it sit in the fridge longer to soak up more alcohol. After 5 hours, it didnt look like much rum had soaked in, and I poured out alot before cutting it up, but sure enough it had soaked in plenty for me. Enjoy.
You can see here the dark spots where the rum is most concentrated. Please eat responsibly!