Disclaimer: Don't own, don't sue. I got this idea because everyone has been asking vic Mignogna (Ed's english voice) to say it. This is my version of how the whole line got started.
"Are you serious?"
"No way!"
"Impossible, Mustang could never…"
"That's what I heard."
"Heard what?"
Everyone in the room turned and looked at the doorway. There stood Edward Elric, back from yet another wild goose chase after the Philosopher's Stone. Behind him, still in the hall, was his brother Al, cautiously peeking in over his older brother's shoulder.
"You boys just get in?" Breda asked, sitting up in his chair.
"Yeah," Ed said, entering the room and joining the group. "I figured the first thing I'ld do is give my report to that rat of a colonel."
"Oh, yeah about that…" Havoc said, giving Hawkeye a smirk. "The colonel isn't seeing anyone today."
"What?" Ed's amber eyes followed the smirk the first lieutenant, who was calmly polishing her gun in a chair in the corner. She looked up and caught the alchemist's eye and gave him a triumphant smirk. "O.k.…"
"She and the colonel had a bet the other day," Falman explained.
"So?" Mustang's business was not on Ed's list of interests.
"He lost," Havoc snickered.
"Wha?" Ed sat in one of the other chairs. Now he was interested. "What happened?"
"Well," Havoc said, leaning towards the pint-sized alchemist. "Apparently whoever lost the bet had to wear-"
BANG!
In an instant all the heads in the office turned to the door of their commanding officer. There, in the doorway, stood Colonel Roy Mustang. The infamous Flame Alchemist, womanizer extraordinaire and the source of Ed's annoyance: wearing a skirt. No, not just any skirt.
A tiny miniskirt.
Roy's cold, dark eyes scanned the room and its inhabitants. He dared them to say anything. For a minute, the glair worked.
And on cue, all the personnel busted out laughing. Fuery fell of his chair, trying to straighten his glasses. Breda smacked his knee and Falman attempted to hide his own laughter. Hawkeye couldn't hide her own smirk and cleaned her other gun.
"Wow," Havoc said, gasping for air. "Colonel Mustang is dead sexy."
"Yeah," Ed said grabbing his aching sides. "In a mini skirt!" This started everyone laughing harder and the pulsing vein on the side of the colonel's forehead get larger.
SNAP
Outside the birds were disturbed by a loud boom from the military's office building.
"You know you didn't have to do that," Hawkeye commented, putting her gun back in its holster. She stood up and stepped over the scorched remains of the desks. "You could have just told them off or something."
"I know," Roy answered. "But this felt a lot better than that."
"I told you that you didn't have to wear that thing."
"I lost fair and square," Roy said, shrugging.
"Well, they did say one thing right."
"What's that?"
Riza leaned against him and stood up to his ear.
"Colonel Mustang, you do look good in a miniskirt."