Borderlands, Sledge, he does a AoE melee thing with his hammer if you are too close to his X axis. Led sledge to the lower platform, and ran around and jumped on the higher, he spammed his hammer attack, and I spam bullets.
Other cheap kills include The Hulk (or whoever the green boss was) in I Want To Be The Guy, where if you shoot early he dies, I did this without even realising there was a boss and my friend filled me in.
Also in Zelda II, after beating the lightning-bird, you have to fight Dark Link, you just run to the left crouch, and spam your sword, whenever he tries to run at you, he gets hurt cause he can not move forward whilst crouching, and if he manages to slide in with his shield, I would not get effected as I could not slide off of the screen.