Standard disclaimers apply, thanks to rosesbud for the beta :)
"Past… participle… can be used in the active…. Or something else…" Clark grunted, a hand on the headboard and the other beneath his wife. The bed rocked with their combined efforts, creaking and clacking against the apartment's shared wall.
Lois' hand raked ineffectually down his back as she gasped. "Active voice or passive voi--" the last transformed into a moan. "It can be a verb or an…" another squeal interrupted the thought.
"Adverb," Clark continued between forceful sighs. "It's a non-infinite verb." He said something else but it was drowned out by Lois' squealing.
When she quieted down to mere heavy breathing and sheet twisting, Clark continued, this time more thoughtful, even though his face was flush as he grew close this own climax. "You know, the old rule regarding split infinitives was based on…Latin grammar. And has no actual bearing on English."
He was lost in the moment, and it took him a few seconds to notice she'd stopped moving beneath him and was looking at him funny. "What? Modern grammar rules state that the split infinitive is now ok."
Both hands on his shoulders, she pushed him away, and he let her. She rolled over, her back to him, looking over the edge of the bed.
"I lost it."
"But I was almost--"
"Nope. The moment's gone." She picked up the hardback book on her bedside table and searched for her place.
"But you LIKE it when I talk grammar in bed!"
She licked her lips and turned the page, not looking at him. "I'm not talking to you right now."
"Need help?" Without waiting for a response, Clark flopped into the chair next to Batman and stared up at the flickering screens filling up the monitor womb wall. He dug his wooden mixing spoon into the bucket of Thin Mint ice cream.
"Trouble at home?" Batman didn't even look up from the screens.
"Don't even start."
"You only come up here when you're hiding from Lois." Batman flicked to another view of the Balkans.
"Anything going on out there?" Superman licked the huge green glop overflowing on his spoon. "Women are aliens, you know that? I'm an alien. They're … way more alien."
Batman gave him a long sideways glance, watching the Man of Steel drown his sorrows in ice cream for a moment. "You didn't mention split infinitives, did you?"
The spoon snapped in Clark's grasp and the ice cream flicked onto the Dark Knight's cape, rolling and sliding painfully slowly to the floor.
"Never mention split infinitives."
Clark got up, sitting the half-full bucket on the chair. "I don't even want to know, do I?"
Batman flicked the remaining ice cream off his cape and onto the floor. "Probably not."