Can drunk people punch straight?

Alcohol acts as an anesthetic that depresses brain activity and the ability to function normally.

Usually not. At the point they are at, they only care about themselves and how they are going to get home, walk, etc.

Because they drink to feel good, and continue beyond that point without meaning to (or are unable to stop, in the case of people addicted to alcohol).

Their vision blurs and or doubles They get tired (sometimes) They can't walk straight They tend to throw up They say weird things you probably can't understand They will have more courage to do...

That depends on how drunk they are. Someone who is just a bit tipsy will still perfectly know what he does. But when you are completely wasted and passed out, you won't know or remember what you do.