A prank that does involve altering body chemistry

I've been looking forward to this for a while. You can see the methylene blue on the left, contained within two baggies as it stains almost anything. The dye seems to have spilled most likely when I stowed it. I didn't add any Ex-lax, but I think it really makes the camera phone picture that much better.
I followed the recipe on the box, although not well. I forgot to add some special chocolate syrup that came with it. I eyeballed the methylene blue until the mix had a distinctive green coloration. In addition to the methylene blue, I poured a bag of chocolate chips into the mix too. I guess I didn't really follow the instructions. Brownie mix effectively hid the usual bitter taste!
It looked disgusting.
Luckily, the green color faded when baked. I'm eating some of the batter now, which is slightly more viscous than usual brownie batter, but still delicious!