This happened years ago and has been going on since.
When I was 22 years old my wife and I got divorced and I started hanging out with my friend Mark a lot more. We spent so much time together we quickly became best friends often showing up at each other's homes without calling ahead and just walking in without knocking.
One day I was sitting in my recliner in my front room watching one of my favorite porns and stroking my cock when Mark showed up unannounced and just walked in as usual. As soon as he saw me and what I was doing he got very embarrassed and started apologizing all the while he never took his eyes off my hand wrapped around my hard dick. I told him it was no big deal and it was my own fault for not locking the door. I grabbed a towel that was laying nearby and covered up my cock but didn't turn off the porn which was nothing but guys jacking off either alone or together. I noticed my buddy couldn't take his eyes off the guy on screen stroking his huge cock.