Chlorine stinger

[Greta]

The act of having anal sex in a [chlorine] treated swimming pool. The chlorine levels should be high enough to leave a nice burning [sting] on the genitals of both parties, although the recipient of the anal sex is typically said to have gotten [stung] worse than the giver.

The act is not specific to pools, however, as a warm bath treated with a substantial amount of chlorine works just the same.