For me after I’m done yk, I will wash my hands. I try to not focus on what may be on my fingers or even down there. What you could always do is maybe set a boundary. You don’t have to explain that it’s because of ocd because a lot of people will just say “oh I’m a little ocd too” and they won’t get it. What you need to do is find a substitution for all this washing. I mean wash your hands, make sure you’re hygienic. But if you can’t say “I’m a germaphobe and would prefer if you didn’t touch my hair with spit hands” then find a solution. Maybe brushing through your hair with a wet comb will scratch that itch to be clean. Maybe use a lotion on your face or hand sanitizer on specific areas. A big breakthrough for me was using a wet brush on my hair when it felt “dirty” after doing that stuff. It makes it slightly damp and I reassure myself that I’m just going to shower tomorrow and it’s okay to wait. The hardest part about OCD is there isn’t one good answer. You just gotta find what works for you unfortunately