All the enemy are running away with about 50 health.
One fiora tiamat basic attack
Pentakill

The entire enemy team is low and as Fiora you ult onto a teleporting TF who's teleporting to the middle of the extremely low health enemy team, taking you with him and giving you the

PENTAKILL

You run by a bush to check Baron by yourself like a noob...... you recently bought Sunfire Cape.

"PENTAKILL!!!"

What the fu-?

Didn't read to see if anyone else posted this, but its a pretty hilarious pentakill.

http://www.youtube.com/watch?v=NovYokP4s4g

Malphite initiates into the dragon pit. Lulu's ult is on cooldown so she uses her shield on malphite but ends up hitting Ashe getting a kill. She then glitterlances and fires at 2 lines of enemies getting her the penta.

Sona ults whole enemy team at baron - baron kills all 5 - PENTAKILL FOR SONA!!!

The enemie team spots a Amumu trying to solo Baron, thinking of stealing Baron, they wait and gank Amumu at the perfect time to flash smite. Unknowing to the enemies, Amumu has prepared his ult to last hit baron(Ap amumu that is terrible but somehow fed). The enemie team 5 man flashes to ensure Baron is secured and to be able to kill Amumu, but just before smiting, Amumu ults grabing himself an unwitting pentakill

Anivia: thornmail while in egg form (have gotten a double before)

http://www.youtube.com/watch?v=NovYokP4s4g

THIS.

If already linked. sorry.

The Entire enemy team all with low health was in a bush, and a cho q`d the bush to see if it was safe rather than face checking