PORT-A-PINT

Bought two of these for a camping trip and they flattened down small enough to disappear in my backpack. The flick-to-extend thing actually works, and once it's open it holds a full pint without feeling flimsy.

Tossed this in my jacket pocket before a concert and forgot it was even there until my buddy needed a cup. It collapses down small enough to disappear but holds a full pour once extended, which saved us from paying for another round inside.

The flick-to-extend thing is oddly satisfying and it actually stays put once it's open. I brought it to a cookout and ended up using it way more than the solo cups everyone else had.