Needles.

Ewh, I think there equally horrible.

i agree with enchanter. they are both pretty bad, why would you wanna do either?

I am freaked out by why you would even ask such a question, but since you did ask, here is my opinion. Without a doubt drinking acid would be the most severe pain of the two choices you posed. Before the acid even got to your stomach it would begin burning your mouth and throat, and the pain would be intense beyond your imagination. Then as you were screaming from the pain, your voice would go silent as the acid burnt your larynx so that you wouldn't even be able to make a sound as you suffered. Swallowing needles on the other hand would at least allow you to scream and yell, and it would allow you to tell someone why you were bleeding out of your mouth as you were gagging in your own blood.

ACID

Well it depends on what we're talking about. Once? All the time?
Once- Needles are worse.
All the time- both are terrible.
Take it from me, tripping a lot of acid in a short period of timeis never a good idea, it can fog your vision, it can turn you into a person you don't recognize. But Acid is still an amazing substance.