Stuffing

I have seen many people get huge after drinking from their shower hoses... How does one do this easily? Tips?

That's really easy - just try!
Dismount the shower's head so that the hose is open ended.

Then let the water flow slowly - adjust the temperature rather too low than too high.

Start drinking from it - and increase the flow slowly until you reach the point where you don't have to chug any more, it simply flows down

It's really great fun - don't forget to weight before/after to measure how much you could chug!

Are you sure they aren't using the hose on the other end

When it comes to bigger amounts you should take care about water poisoning.
Since I reached the 3L level I simply have a big meal an hour or so before chugging, that limits the (water-)capacity

By the soft pressure from the water hose and when your throat muscles are relaxed.

Too much water can kill you.

en.wikipedia.org/wiki/Water_intoxication

Use caution.

It's true too much water can kill you. But it takes a lot of fracking water. Usually one will puke it up before one even get close to that amount. I'd say it's more something to keep in the back of ones mind rather than worry about. Myself I have consumed over a gallon of water with no ill effects and I don't think I was right on the edge of death. Just my two cents.