Oh, boy. I already posted in the 'fantasies fulfilled' thread, but since this one is open to non-swinging...
I'm about 22, I used to fool around with a 30-something latina who hated her live-in boyfriend's guts. She'd drop by my apartment downtown maybe once or twice a week. (Not the most ethical situation, but the guy really was a clown and I didn't give it a second thought, being at an age where I was more than happy to get in wherever I fit in.) One day, she's riding me and when she gets a glimpse out the window, goes "oh, shit". It's a third-floor walkup and she's looking down at her boyfriend on the sidewalk, trying to figure out where she went. This doesn't stop her, she just keeps an eye on him while she keeps working my cock. After she cums, biting her lip and all that, while looking down at him, she gets off, removes the condom, finishes me in her mouth like it's an emergency, spits into my kitchen sink, gets dressed and goes out the back window and down the fire escape to sit in a bar on the other side of the courtyard behind my apartment and text her boyfriend like that's where she's been the whole time.
We timed our meetups a little more carefully after that, she finally kicked him out not long after.