When two nerds challenge eachothers skill at a video game, trashtalking about the stupidest things ever. People ask for them on youtube, usually after seeing a gameplay montage. 1v1's will always be posted on youtube. They have descriptions like this:
so i ran in2 dis random in ranked, and this kid was talkin shit an i 5-0ed him
x S IN ii p3 R: aight dawgs dis is ma 19th sniper montage dis is 4 da fans an haterz keep hatin
oOSC0P3SOo: dude ur trash
x S IN ii p3 R: stfu n00b
oOSCOP3SOo: 1v1 scrub
x S IN ii p3 R: i dun play bk's. stfu random
Generally posed as a question, it literally means "One versus one", but is used to communicate that someone wants to take an issue to the gaming "arena" and prove his might and superiority. Essentially, its nerd for "You wanna take this outside?"
Nerd 1: HAha...I hax0rsizord joo..N00B!
Nerd 2: 1v1? (indicating he wants to take this to the "arena" and prove his superiority at gaming)