2 years ago was on a 6am (approx) DEN-IAD A-320 (If i remember correctly). Was working late and didn't sleep the night before. Full flight and was in E+ isle with a passenger of size next to me in the middle seat. Both armrests had to be up for the flight and no one in our row could use the tray table for our drinks. I think I was more embarrassed than he was. Hell of a nice guy but I obviously looked for another seat after take off (I couldn't sit with my shoulders straight). Flight attendant saw me and said they were completely full but I could hang out in the back with them if I wanted to take breaks, which I did. I was a bit miffed due to my lack of sleep and inability to use the armrest of tray table but let it go. Didn't complain or anything to CS as I felt the flight attendants were as accommodating as possible given the situation. Yes United probably should have made him buy 2 seats if he couldn't fit between the armrests or tray tables for his neighbors... I figured the guy has worse problems than me not sleeping or being comfortable for 3-4hrs so let it go....