What is it with people having sex in an elevator?.

I just fixed the last problem in the group controller in a 4 bank of neglected dovers. I was on my way out for the day checking the cars one last time and the number 1 car stops about 2 foot or so above the first floor. I heard the arrival ding but no doors? So in a panic I open the door to the elevator to see if anyone was trapped and there was a very old and I mean old, nurse and a porter just banging away. I knew these two from around the hospital. Let's just say we were all embarrassed. But none more than the 60 year old nurse pulling here panties up in a shameful rush. And the porter running down the hallway trying to put away and hide a boner. It was 4:00 on a Friday so the 4 bank lobby was full of people. Glad it wasn't my grandparents. EWWW was most definitely the words that came to my mind. Oh yeah and they were both married, just not to each other. Neither of them could look me in the eyes for a while. I so wanted to just "bark like a dog" every time I saw one of them