When you got the beer shits real bad, and a big turd floats to the top of the toilet bowl. That's a rum floater.
The bartender at the pool wanted to know if I wanted a "rum floater" in my Pina Colada, but I had the beer shits real bad and already had a rum floater in the shitter just this morning.
After a night of drinking rum, you wake early the next morning and shit a super hard brick that stretches your anus to painful extremes but has a clean break. Its usually followed a little while later with an epic dose of the runs.
*limping back to bed* Morning wifey, I just shat a rum plug, you have an hour to use the bathroom before I need it again.