The act of having sexual intercourse of the anus through telepathy, often the person being targeted has no idea it has happened until the point where they spend the rest of the day feeling as though there is something up their ass
Jim: watch this man,im gonna have butsecks with that guy over there Tim: r u for serious?
Jim: look... now he's walking around like theres something in his ass
When the spy, featured on the PS3, and PC game, Team Fortress 2, attempts to stab you (one of the 8 other male characters) in the back, but instead, gives you "Surprise Buttsecks" after, the trending songs and videos on YouTube.
*The Blue Scout, is defeating the red team when suddenly-*
Spy: "SURPRISE BUTTSECKS", BUTTSECKS, B-B-B-B-B-BUTT-SECKS!!
A: Me and my gf had a really romantic datelast night. Saw titanic.
B: nice
A: yeah, and then when that stupid boat sank, i gave her surprise buttsecks!!!1 kekekekeekk
B: WTF??