Dave says that your drinking container reveals your philosophical side.
Janet, being a teacher, only uses mugs that she gets as free gifts.
At Geospiza, I use the communal mugs that I find in the cupboard. Most of these mugs seem to come from now-defunct biotech companies who handed them out at meetings. One of my all time favorites, though, is a really cool mug that I got from Betty Kutter with a picture of phage T4 and a map of its genome. The pictures are getting worn away, but I still like the mug.
At home, I drink out of these:
One of these mugs was a gift. I made the other two mugs, and in case you're wondering, I use the proceeds from selling coffee mugs and T-shirts to help finance Geospiza's Education program. This allows us to help and occasionally donate books and CDs to activities like this.