Boyfriend has a gross request?

My boyfriend has a gross request. He likes the inside of his ear licked (deep). Admittedly I did it once, but the whole thing grosses me out. To make things worse, he's a biochemistry major and told me about how he had to grow bacteria in the lab once. well he scd the men's bathroom, the biology lab and his ear. The ear swab had the most bacteria. Ever since I heard that, I can't make myself do it again no matter how much he likes it. What does everyone else think. Should i just get over it for his sake?