Notes: NatsuLucy is this fandom's currency. Admit it.
Spice It Up
There are several plausible reasons (excuses) for why Natsu's taking her shirt off. Maybe…
a) He's actually a fully qualified doctor and is helping her to prevent breast cancer
b) He tripped…upwards
c) The damn hormones
d) He and Happy were playing hide-and-seek
e) Gray bet him a fifty that he wouldn't do it
So while Lucy's flustered and giggling and—cold, because holy shit, did they really have to do this in the freezer? This was almost as bad as the beach, (sand in awkward areas is possibly the least romantic thing ever) but still, she is willing to forgive and forget, so long as he pulls her closer than close. (Natsu's a fire mage. Of course he's warm. Really, it's all very reasonable. This was all being done in the name of science, after all. What was it that psychologists call it these days? Oh, right, experimenting.)
So then they're both…casually chilling, (no, seriously) without shirts on, and Natsu's eyeing her bra like it's some kind of medieval torture device, when Gray walks in.
Lucy starts shrieking.
There are several highly likely reasons for Gray's untimely entrance. Maybe…
a) He was hungry, and if the two whippersnappers were going to get frisky, maybe they shouldn't do it where the ice cream was stored
b) His personal calling in life was to make Natsu's life as hellish as possible
c) Lucy was hot, and shirtless, and he was a teenage guy
d) He secretly believed her breasts were inflatable, and wanted to see what was really going on
e) He needed money, and as far as blackmail went, this was priceless
"Oh." Gray says, and studies the floor. Natsu clamps a hand over Lucy's mouth when she fails to stop squealing, and glares at Gray. His status was quickly going from 'rival' to 'evil demon overlord that must be obliterated at any cost.'
"Are you trying to make me kill you?"
Gray narrows his eyes, "Dude, there are hotels for this sort of thing."
"I am not a hooker!" Lucy screeches around Natsu's palm. Gray points at her shirt. It's sort of on the floor. Lucy proceeds to hide behind Natsu.
"We could always kill him," she suggests, "Then he wouldn't talk."
"Why should I care if he talks?" Natsu mutters, sounding almost sullen. Gray sneers at him.
"In the cooler? Wow, classy."
"Oh, right. As if you could do any better."
"I would," Gray says indignantly.
He probably can. Natsu ignores this.
"Could you just go?" Lucy mutters, sounding like she's gone beyond embarrassment and dropped into frighteningly calm, "And never speak of this again?"
Gray frowns, "But I sleep in here." Abruptly, a rather horrified expression crosses his face, "Oh, God. You guys are doing it in my bedroom."
"…Whatcha gonna do about it?" Natsu challenges.
There were several things Gray can do about it. Maybe he'll…
a) kill him
b) kill him slowly
c) sell his Pokémon card collection
d) subtly ogle Lucy
e) call Erza
"I'll call Erza," Gray threatens. Natsu actually takes a step back.
"Oh, I would."
"…We aren't going to make out anymore, are we?" Lucy mutters grumpily. Neither of them appear to hear her.