Sitting on top of my dresser I have one of those old Nalgenes that leeches chemicals into your water. I use it to mix plant food before I water my houseplants, but it's not marked in any special way. Every time I look at it I'll consider that I should draw a big skull-and-crossbones on the outside. It's only a matter of time until some house guests sees that I'm out of clean glasses and decides to make use of this toxic Nalgene. I hope that never happens, but if it ever does, I'll take great joy in running over to them and kicking the full Nalgene away from their face at full stride before they take their first sip. I'm sure they'll thank me.