When you put a
cup with a drink inside on a surface, and then take it off. It leaves behind a ring-shaped formation of what you just drank. This is the result of spilling some of the drink over your cup a little bit, so some of the liquid trickles down the the bottom and stays there. Other times, it's because you
shook the cup while it is still on the table, thus the liquid collects at the bottom part of the cup. After a while, it will leave a sort of dried up ring, except with the
case of
water, it usually evaporates. See
water ring for cups with
water. That dried up mess is what you call a "residue ring." Note that this can also happen with bowls, plates, pans, pots, aluminum cans, circular objects, etc. It is usually found at parties, messy houses, kitchens, and such.
Mom (After a
Party): Omg, these friggin' residue rings are
annoying to get rid of...can you help me son
please?
Son: Mom, many of those were from you...