Clever riddles with simple answers

Whoever makes it, tells it not. Whoever takes it, knows it not. Whoever knows it, wants it not.

What loses its head in the morning but gets it back at night?

I have more than 80 keys, but I cannot open any lock. What Am I?

What word looks the same backwards and upside down?

What is the ancient invention that allows people to see through walls?

What kind of soda must you not drink?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

General Custer is surrounded by Indians and he's the only cowboy left. He finds an old lamp in front of him and rubs it. Out pops a genie. The genie grants Custer one wish, with a catch. He says, "Whatever you wish for, each Indian will get two of the same thing." Custer ponders a while and thinks:"If I get a bow and arrow they get two. If I get a rifle they get two!" He then rubs the bottle again and out pops the genie. "Well," the genie asks "have you made up your mind?" What did Custer ask for to help him get away?

What word does this rebus represents? meta meta meta meta

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?