That's hysterical cause I do that all the time

Not at all. I have the flip straw Stanley cup and it is ONLY used for water. I do not put anything else in it whatsoever.

You have to wash it still... your mouth has so much different bacteria and it goes onto the cup and morphs into other bacteria. Water bottles that have a clear straw you can see them start to get a yellow film cuz it's all concentrated in one compact and see-through area, but the bacteria that causes that gunk will exist less visibly on a water cup you use without washing with soap too

This reminded me to go wash my water cup

Fun fact bacteria also likes water 🙄

If you the only one drinking from your cup how you choose to operate is your business. I ain’t judging.

This is the equivalent of not washing your legs cuz the water runs down