One of Kung Lao's fatalities where he beats his enemy to death, with a bunny rabbit.
Even funnier, he has one where hands the bunny to the enemy, only for the bunny to maul them instead. And the enemy even pets the bunny before being mauled! Doing this one to an Oni or a Tarkatan may be simply hilarious.
Cage provides a few as well. Like kill-stealing Goro or his new Ball-Breaker fatality.
What about beating Shao Kahn to death with Kintaro's freaking severed head? Its a viable tactic too, considering it does some good damage against him.
An unintentionally hilarious moment occurs right before you battle Baraka. Baraka toys with a monk he has impaled on his retractable spikes. When Baraka notices the Shaolin Monks arrive, he decides to do away with his captive and impales him through the head before tossing him over to Liu-Kang. Liu Kang's immediate reaction to all this...is approaching the monk's corpse and asking "Are you okay?". WOW.
Then there's Scorpion. If you dodge his spear attack on too many times, he will either say 'GET OVER HERE, BITCH!' or 'GET THE FUCK OVER HERE!'
Kung Lao's constant teasing of Liu Kang over Kitana being the latter's girlfriend is so high-school jock-like of Kung that its impossible not to laugh. It almost makes one think that they were aiming to make "She's not my girlfriend!" Liu Kang's new catchphrase.