what are the foamies?

I've seen mention of it a few times, not really sure what it is, but sounds pretty unpleasant! What's the 'foamies'? and what causes/how can you prevent it?

The description I read a bit ago was the build up of saliva like you get when you are about to vomit.

For me, it is when I eat too fast, or more than I should, I start to salivate and feel like I am going to be sick.  I also feel like I cannot breathe and some pain in the area where the esophagus connects to the stomach.

To avoid them, chew chew chew, eat slowly, and measure to ensure you are not eating too much.

Foamies is actually a bit more than just saliva in your mouth. You do actually vomit, but instead of any ingested food or drink coming back up you get a stream of bubbly foam. Sometimes it takes a few heaves for it to finish. If you get it, it's unmistakable, and you'll know exactly why it's called "the foamies". 

The prevention is exactly what's been said: Chew well, eat slowly.

I can get the foamed by just not chewing well enough and swallowing a piece that is to big. It seems to back up all my saliva and creates 'foam' which overflows into my mouth, which I then have to spit out, because I can't swallow because of the piece of food that feels like it's blocking my pouch.