Yeti Tumblers (coffee to-go mugs) are so great at keeping hot drinks hot drinks and cold drinks cold (I’m a huge cold brew coffee fan, year-round), but an important tip is that you have to disassemble the tops occasionally and clean them, as mold can build up inside the rubber gasket or under the mag-slider (I just run them through the dishwasher disasembled every few uses).

I saw this YouTube video a while back by a doctor talking about a patient with recurring bacterial infections, which were caused by this!