Did you ever notice that the flag Mario takes down at the end of each level has a peace symbol on it? This might indicate that all the Goombas and Koopas in the original Super Mario Bros game are peaceful beings and is probably why none of them seem to want to kill Mario in the first worlds, but as the character continues his killing spree, the creatures of the land fight back.

Seeing how violent Mario can get I bet princess peach left him for Browser, who has many castles and lots of coins.

Super Mario Brothers is a game about kidnapping your ex girlfriend.

[Via]