my (24f) boyfriend (27m) drunkingly told me he had a fantasy of watching me go poop

throw away account for obvious reasons. my bf and i have been together for 4 years now and we’re extremely close and have an overall great relationship; sex, communication, all of it. we also share an apartment together. the other night we got pretty tipsy from some wine and he asked if i had any sexual fantasies i’ve never told him about. i told him sometimes i fantasize about him with another women, but other than that i have nothing crazy. he told me there was something he’s always been afraid to tell me and that he’s never told a soul before because he’s embarrassed. i’m like ok it can’t be that bad, and so he told me. he said the thought of me sitting on the toilet to go poop turns him on. he said he’s not interested in “playing with it” or anything (BARF) but the sole act of me pooping on the toilet and him being able to listen and watch is a huge turn on for him. i’m shocked because i would have NEVER expected this from him..he’s a completely normal guy, popular with a lot of friends, great looking and not in any way creepy. i know everyone has sexual fantasies and some are taboo like this. i’m not judging him because i love him and i know it took a lot for him to open up to me like that but also wtf. he told me he would never expect me to let him watch or anything it’s just something that really turns him on and he doesn’t understand why.

any advice on how to approach this situation would be greatly appreciated.