What's another name for coming inside a woman?

This joke is an example of a double entendre, where a phrase is used to convey two meanings, one of which is often risqué or inappropriate. In this case, the joke plays on the two different interpretations of “loading the dishwasher.”
In a literal sense, “loading the dishwasher” refers to the mundane household task of placing dirty dishes into a dishwasher for cleaning. However, the joke uses this phrase as a euphemism for a sexual act, specifically ej*culating inside a woman. The humor (which can be seen as offensive and sexist by many) arises from the unexpected and crude comparison between a household chore and a sexual act, juxtaposing the mundane with the intimate in a surprising and shocking way.