Three-legged bloomers

Three Legged Bloomers are a form of bondage clothing, normally, “Found in Europe.” They are a pair of pants that, “Have been modified by a slit in the crotch.” The bottom fits their head into the slit as a sort of hood, with holes on the side for breathing. This forces the bottom to focus on the tops genitals, and give them oral sex. These pants are, "Made either of some thin material or latex."

References

The Encyclopaedia of Unusual Sex Practices by Brenda Love. ISBN – 0862882230