I've seen "thought experiments" (not sure they're quite that, but close enough) like that for a variety of things. The big numbers I've seen that done for most often are: unique shufflings of a deck of playing cards (about 10^68), atoms in the universe (about 10^80), and a googol (10^100). I've definitely seen the playing card one involve the walk around the world, pile of paper, grand canyon, etc (also drain the ocean a drop at a time, IIRC).