Gokudera absolutely hates popsicles.
It's not that he dislikes the cold, or the stickiness, or even the ache he sometimes gets against his temples when he eats them too fast. Even the issue of melting isn't a problem; even on the hottest of days, Gokudera eats his so quickly they never have time to even begin melting before he's sliding the last bite off the popsicle stick.
The problem - as it so often is - is Yamamoto Takeshi. Specifically, the way Yamamoto Takeshi eats popsicles. He's slow about it the way Gokudera isn't, lets the ice soak in the summer heat until the ice is melting sticky over the tops of his fingers, sometimes until the whole thing is sliding off the stick completely. That's frustrating to watch, makes Gokudera edgy as he watches the inevitable mess collect against Yamamoto's knuckles, but that's not the problem either, not exactly. Far worse than Yamamoto not eating popsicles is when he does eat them. Gokudera bites the ice, himself, snaps off chunks of sweet cold and crushes them over his tongue, but Yamamoto doesn't bite popsicles.
He licks them.
It's awful to watch. Gokudera has to brace himself for it every time Tsuna suggests they get a treat on the way home from school, has to steel himself to watch the slow slide of Yamamoto's tongue against the ice in his periphery. All the popsicles in the world can't cool the heat that motion pulls under Gokudera's skin, the way his breathing catches sticky in his throat when Yamamoto idly slides his mouth down over the half-melted popsicle. Gokudera can see the ice melting under the heat of his mouth, can watch the way Yamamoto's tongue slides unconsciously across the sugar caught at his lower lip. He can imagine the way that tongue would feel against the hot flush of his skin instead of the chill of the ice, is sure without testing that Yamamoto tastes as good as the popsicles they eat. He can imagine the cold of the ice lingering over the heat of Yamamoto's tongue, wants to lick the cold and the sugar both right off his lips until there's just the warm clean taste of Yamamoto himself.
That's usually the point he has to look away, or try to. If he's lucky Tsuna will keep talking to Yamamoto and leave Gokudera to suffer through the burn in his blood as well as the heat of the sun on his skin; if he's unlucky Yamamoto will try to pull him into conversation and he'll have to try to talk around the growl of desire caught at the back of his throat.
It always concludes the same way. Sometimes they make it all the way to Tsuna's house before Gokudera's patience snaps and he pulls Yamamoto the rest of the way back to his house. Sometimes Yamamoto is still in the middle of licking his fingers clean when Gokudera makes some half-formed excuse about studying and drags Yamamoto into the closest shadowed corner he can find. It never matters where they end up. Whether they're in the corner of Yamamoto's bedroom, or pressed against the inside of Gokudera's front door, or ducking into the cover of a deserted alleyway, Gokudera always ends up sucking the sweet cold of the ice off Yamamoto's lips, swallowing the whimper of satisfaction Yamamoto makes to soothe the ache of want at the back of his own throat. He doesn't even care when Yamamoto's sticky fingers catch at his hair, or the way he always ends up hotter than when they started, or how Yamamoto doesn't always make it home after and shows up at school the next day in the same rumpled uniform he was wearing the day before.
Gokudera hates popsicles, but he loves the way they taste.