In a spaceship? He is the spaceship... or was at least. "Hmmm... Oh... average size ranges from about ten to twenty feet... and up..." He's assuming the measurements that he's learned here apply to both his world and John's, but he can't be too sure.

Arriving at the bar, he sat down outside on the edge of the patio and ordered a barrel of decent beer, before pausing a moment. "Do you want something different, or would you just like a couple of mugs out of mine?" Because really, it's not like a pitcher or so taken from the barrel, or adding a different drink order will make much difference.