Pan-galactic gargle blaster

In one of life's mysterious, unexpected twists:

There's a friend of mine (a catholic lady, the sort who drinks alcohol for religious reasons, among others) who has a shot-glass collection. She's traveled to many strange places, and picked up one in every city she's been to.

There's, of course, as such things go, another friend of mine (a muslim man, the sort who won't buy me a drink if he was taking me out to dinner) who also has a shot-glass collection. In his own words: "My parents would travel, and get me up the smallest thing they could buy."