Most likely originated in the armed services, probably during
Vietnam. "Kick ass" is generically applied to beating the opponent, whereas taking
names refers to killing the enemy, or "taking their names." Has been adopted into
common usage as a general motivational statement.
"CHARLIES OVER THAT RIDGE, LETS
KICKASS AND TAKE
NAMES!"
"pick up that goddam football damnit! now get out there, kick ass and take
names you pussy!"