How to try not to throw up.

Actually, throwing up would actually be a good thing, even if the experience is...unpleasant.
Your body's simply trying to get rid of something considered "toxic" to it, and it's getting out by making you "throw it back up".
However, if you're really determined not to throw up, then read link.

Close you're mouth drink some water lie down and sleep

ur prob better throwin up 2 get it outta ur system youll feel betta afterwardss

If you have to let it out then let it out.

I know having leftover food come out of your nose is gross but it's better out then in.