You'll probably scream like hell.
if i remember right, battery acid is concentrated sulfuric acid. with a gulp, horrible burns are guaranteed, i bet it is also horrific for your teeth (loads of calcium -> no more teeth). you might survive it depending on how quickly you spit it out and get to water.
seriously, do very much try to avoid that.
udpdate: no, if he isnt screeming it wasnt that concentrated. anyway. in science class they dont let you play with sulfuric acid above 1 M,, thats kids stuff. your friend should nevertheless avoid being an airhead and take everything into his mouth. geez
upd. his lying on the floor dead might be a reason he's not all that chatty, yeah... feeling stupid and ashamed and therefore not in the mood would be another one? nauseated? (in which case i hope he had the good sense to go see the doctor)
DON'T DRINK WATER -- use it to wash out his mouth, but don't swallow
hahaha, shutup ***** swallow!
Well you know its acid.... so drink a lot of water and see your school nurse for more help. If he has stomach ache or burning sensation then see a doctor to be safe.
Drink plenty of water to flush system and then drink milk to coat your stomach,contact poison center nearest you at once!
Battery Acid exposure can cause many different health problems. Some problems don't occur until later. Swelling, pain etc.. It's not a very nice thing to have in your mouth. I would contact a poison control center right away!