“Confidence coffee”.

Let me explain; when you go on stage, you’re nervous and you need some water because your mouth dries out. Bring water in a mug/travel mug.

It’s self regulating. The dryer your mouth is, the more you need to drink water. The more you appear to sip coffee while publicly speaking, the more relaxed you look.

Compare to swigging from a water bottle; your nerves are on public display.

Confidence coffee=water in an opaque coffee container.