The back row in a theater, sports arena, or church. Since they're often dark and secluded, they're theoretically the best place to get a handjob, without being seen by some fuckwipe.
Joe: Duuuuuuude we should've gotten our tickets way sooner- we're stuck in the back row.
Bob: Ha says you - me and my girl always wanted handjob seats.
Joe: Oh yeah? I'm gonna sit in the third row. Whatever seat I sit in is the handjob seat.
Seats in a theater, usually for a live show of some sort, that are so high and far away from the stage that you get a "nosebleed" from the high altitude.
"Where were you for poker night, man?"
"Oh, man - My girlfriend dragged me to the opera! The show was horrible AND we had nosebleed seats!"
"Rough, dude."
The act of concealing your handgun under your car seat. The car manufacturer Audi, and a few others placed a built in compartment underneath the driver and passenger seats for storing items. This compartment can be used to store your firearm.
Example 1. "You better watch yourself tryin' to run up on them after bouncin' from the club, I heard they got the heated seats"
Example 2. "Me and my boy both keep our burners under our seats, xd40 n glock 40, we got the heated seats baby!"