I really don't think advocating illegal psychotropic drugs is something you should do here.
Anyway, watermelon has a lot of really good antioxidants, most of which are found in the seeds which have to be crushed to access (won't do so well swallowed whole). A lot of times if I don't have time for a decent breakfast I'll put watermelon in a blender and mix it 'till the seeds are good and mushy and drink it down. It gets close to my calorie and carb needs and definitely not a bad way to start the day.
Oh and some C.S.C.S. posted an article talking about it being good at breaking up subcataneous fat deposits but personally I just think that's because it has a lot of water in it and if you read Jodi's post about why water is good for losing weight I won't have to waste my time typing it all out