If you’ve been given a very tight design brief where the client specified everything – size, material, color, etc., and are whining that there is no scope for innovation or design, this TROFE mug from IKEA may inspire you a little. The tiniest of detail – a little gap in the base of the cup that helps drain the excess water after you wash the cup and turn it upside down.
This is great design, in my opinion. You can always still be clever in every space and every detail.
That little notch in the base is actually for a different purpose – not the one you describe.
If the cup has a wet bottom and is placed on a coaster, suction can be created as soon as the cup is lifted and the coaster comes with it!
By introducing an air leak in this way, the coaster stays firmly planted on the table top.