I love my friend "Sam" (name changed) dearly but his social skills can be SUPER inappropriate. When we're alone he's sweet as can be, but with new people, after a few moments of meeting them he will start to ask very inappropriate and intimate questions or talk about inappropriately personal things, like details of his sex life (how many times can I say 'inappropriate' in one sentence?). I think that he really thrives on the attention and prides himself on being so "open" about things that are considered by everyone else as "private." We've been friends since high school, but his immaturity has really put distance in our friendship.
He is being brought as a guest to our rehearsal dinner. I intentionally did not invite him to the rehearsal because of his awkward and offensive outbursts (my fiance's family is pretty conservative), but someone else (who is in the wedding) is bringing him as a guest, and I'm not about to tell someone they can't bring their guest of choice because his behavior is offensive.
As shallow as this sounds, a part of me is afraid of being judged based on my friend. I mean we're talking about my future in-laws...is that understandable? But I'm also of course worried about him offending someone by asking if they like blow jobs, or something (seriously...he could do it).
Advice?