Answer:
If you are unsure how to use one then just ask a flight attendant.
Other terms for this handy device include doohicky, doo-dad, and whatchyamacallit.
This is the drinkable phase of matter
What is something yet nothing, but if you fill it up it will disappear?
My second is performed by my first, and it is thought a thief by the marks of my whole might be caught.
In all the world, none can compare, I am a tiny weaver; my deadly cloth so silky and fair. What am I?