most people enjoy doing a thesis paper on something that is happening currently. I have students that are doing their thesis on the gun control debate. Just pick a topic, figure out your stand in the...
It should leave no doubt in the reader's mind as to what the essay will be about.
My opinion on soccer is that is a really fun sport and a good way to have fun.
You could write a thesis on the pros/cons of natural food preservation (ie: canning) vs chemicals used for food for preservation.
talk about the nervous system