Dan's legs shook violently, and he ripped off his pants. The skin on his thighs and calves was turning a disturbing shade of turquoise, and his feet were becoming thin and flaky. They looked a lot like fish fins, actually. Oh dear.
His legs began to fatten, and they moved towards eachother, merging into a scaled tail. Gills formed above his waist, and he cralwed towards a swimming pool...? (newly installed courtesy of Kat) and dived in.
His head emerged from the water. "Now", Kat said, "I've arranged to meet Susan in 30 minutes. Make sure you're ready!"