first of all oranges have peels. not shells. and according to your theory, applying toothpaste would cause some kind of fungus to grow which, in theory, would make you trip. but, since you have no control over the fungus that is growing, yea you might trip, but you might die if you get the wrong one. i wouldnt do it if i was you, just get some shrooms instead of cultivating fungus on orange peels. IMO