i froze a pint of peach schnapps is it okay to drink?!
Your friend is wrong.
First of all, alcohol can't freeze (or more exactly - it freezes at a lower temperature than water and things containing water, like many foods, drinks, etc). So what actually froze in the schnapps is the non-alcoholic parts of it.
And second of all, freezing it (or anything else) doesn't turn it into a poison. I've never heard of anything you can eat or drink that becomes poisonous after freezing it - most things aren't affected in any way by freezing them.
Your friend is incorrect. You can't freeze alcohol in the first place, and if you could it will not turn poisonous.
Slept through science class? How can you be 21 and think that?