Visiting our grandmother, archtypical white haired lovely old lady, we went and rented VHS videos to occupy
some time- I saw a copy of 'Better Off Dead' and happily rented it for me and the younger sibs.
Of course I had completely forgotten the scene he's in the back of the station wagon and they are getting it on under a blanket and his girlfriend suddenly asks "It broke?" (i.e. condom.)
I was probably 15ish and there were a bunch of kids younger then me, and of course Grandma was in the room... AWKWARD.
Of course there was also the time, minus grownups, where I was dropped off with the younger kids to take them to a Disney movie at the strip mall. We went in and somehow managed to go to the wrong theater- it took me a while to realize the Best Little Whorehouse in Texas wasn't just a trailer, but the actual movie, before I hustled everyone outta there.