Chemistry, because there is lots of acid involved.
I don't wish for a lifetime supply every time I smell patchouli.
Namast (nah-ima-stay)
He doesn't pick up after himself.
They kick a Can
Because they spend such a lot of their time in courts!
Because they have a quidditch.
Guac-A-Mole.
He tripped on acid
Someone drops the acid and someone drops the base.
Barium
Chemistry, because he knows a lot about bonds!