"Tell you what…", says Frieza, "Because I'm in such a good mood today, I'll let you have the first shot."
Robin doesn't waste any time in taking advantage of Frieza's overconfidence. A flamethrower of of hot flames sprays all over Frieza. The embers clear just as quickly as they struck.
Frieza is standing there with a big smirk on his face. "Just as I had expected, you are nothing but a....-sniff-....something's burning...." Frieza looks behind him to see the tip of his tail on fire. "AAAAHHHH!!! HOT HOT HOT!!!!!", shouts Frieza as he hits his tail with his hands to put out the flames. After the flames are out, he looks at Robin with a very pissed expression on his face. "WHY YOU LITTLE!!!!"
Frieza extends his hand out and with his index finger pointed straight at Robin. "DEATH BEAM!!!", yells Frieza as he fires a reddish-pink laser-like beam at Robin. Robin uses her quick thinking and puts up a barrier of fire before the beam reaches her. Alas, it is no use. The beam easily penetrates the barrier and slices through Robin's stomach as if it were melted butter. Robin falls backwards as she coughs up blood. Her glasses fall off her face and shatter as they hit the ground.
–FRIEZA ADVANCES!!!!--
Frieza steps on Robin's wounded stomach, pinning her down. He then points his index finger right between her eyes. Tears are running down Robin's frightened face. "Time to turn out the lights.", says Frieza sinisterly.
"STOP!!!!"
Frieza looks to his left to see Goku standing in the isle of the entrance to the arena. "Don't do it Frieza! You've already won the match! You don't need to kill her!", yells Goku. A huge smirk appears across Frieza's face. "Oh really?" A tiny ball of reddish-pink ki appears on the tip of Frieza's finger. Goku clutches his fists and yells louder, "PLEASE FRIEZA!! I'M BEGGING YOU!!! DON'T KILL HER!! SHE IS STILL ONLY A TEENAGER!!!" Frieza chuckles lightly and brings his hand to his side, "Alright monkey, have it your way. I won't kill her."
Goku smiles, "Thank you Frieza" He turns around to go back to the training room, when suddenly he hears the sound of a beam being fired and an soul-piercing scream. He quickly turns around to see Robin lying dead on the ring floor, blood gushing out of a hole in her forehead. Frieza shrugs sarcastically, "Oops, my hand slipped. How clumsy of me. AAAAAAHAHAHAHA!! AAAAAAAAAAAAAAAHAHAHAHAHAHA!!!" With that, Frieza takes off to the opposite arena exit.
Goku grinds his teeth together, "You will pay Frieza. You will pay…."
VS 
I never would of thought of throwing Goku in there.