Green slime.

There was a school assembly about how smoking is harmful. They taught us about the Cilia, little hairs inside the lungs that keep foreign objects out.

They wanted a volunteer to come demonstrate what happens to the cillia when you smoke. They asked for someone with a good sense of humor so I volunteered.

They called me the very silly cilia and dumped this green slime on me. The rest of the students were expecting humor so I started punching the slime that dripped off of me. The students enjoyed it.

Crude oil, from misjudging the pressure when I released a valve at an old job. No ppe, so that stuff got everywhere.