Hah, found one!

That's Feels Like Falling in Love, by Wendy & Tracey.

I've been wanting to use this quote <g>

Quote
"Clark, I do *not* want to grope your ch - *what* have you got on under your shirt? It's all shiny and..." She trailed off. To his satisfaction, she was looking slack-jawed. Thunderstruck, in fact.

"That's... Superman's suit, isn't it?"

"It is." He waited.

"Why are you...?" She halted. Swallowed. Blinked several times. Then, in a strangled voice, continued. "Clark, tell me you're not Superman."

"Sorry, Lois, I can't do that." With the note of amusement that had crept into his voice, he heard himself sound exactly like Superman.
laugh