(noun) An event of failure of such great magnitude that it exceeds the maximum negative measurement of failure (an epic failure) and loops to the maximum level of win instead.
Similar to measuring time on a round clock, being late by several hours at today's event (fail) will cause you to appear early for tomorrow's event (win) because of the buffer overrun of failure.
"When Erika sang vocaloid songs at karaoke, it was so bad that it was buffer overfail and I couldn't help but love her for it."
"The school discontinued playing polka-yodeling during detention when the students starting playing it at school functions. Apparently the punishment achieved buffer overfail and became popular."