I've only experienced this if I've given my husband oral directly after eating a full dinner. That's the only time I can think of that his semen ever made me have nausea like that. Maybe it's in relation to when you've last eaten before you engage in sexual activity? Sprucing up your sex life can be as easy as learning the best oral sex tips. Here are a few tips on how to give oral sex and take your sex life to another level.