When you subscribe to someone on YouTube, hoping for "Sub for Sub," but they don't subscribe back.
Tr0llinN0NST0P was hoping to get a "Sub 4 Sub," and subscribed to NYANRainbowz. He checked his channel later, realizing he had experienced an unrequited sub.
by TehPurpleIce August 15, 2011
Can you define these popular missing words?