I always eat a sandwich and drink a pint (of water you blokes!) on the
flight line before launch.

Two camelbacks, one on each side, one with 50% ice (yanks like it cold
you know), with the tube velcro attached to the side rail. Sat on a
tube one time too many. Besides a wet backside you can't get at it to
drink in my ship! Nice to know where the tube is every time. Hardly
ever use the 2nd camelback at all but it is nice to know it is there
whatever happens.

Energy bars, no chocolate ones as they melt, remelt, and get really
nasty. Like to take some type of candy, usually altoids, with a few
ibuprophen (sp?), in the tin as well. I have a bad back and after three
or four hours the Ib really helps when needed.
Cold beer from crew upon landing and after the ship is in the box.