||and explain that while God may sex to act as the glue to hold married couples together, and to enable the human race to spread and prosper, you intend to do neither, and just want mindless rutting pleasure. They will give you a condom, form which you may be able to make a gasket.
Failing that, try walking through the parks and alleys of the fasionable section of town there the devotees of English style love who practice the falsely labeled safe sex will litter the ground with their left overs.
Or, go to a hardware store and look for a sink-pac, a cheap, $1.19 containier of gaskets and O-rings. One of them should work.