He was UNDER COVER. His cover was a sailor who had just lost his job--the coming on to Toni Taylor bit was PART OF HIS COVER.
As for the part where he threw her into a dumpster, and the part leading up to it . . .
He didn't really have much of a chance to think of what to say before Toni came into the room there. True, what he did say (blowing Lois's cover) was a major faux pas, but we all know how much trouble Clark has with thinking of excuses/cover-ups under pressure (Cheese of the Month Club, anyone?).
As for the dumpster, the bouncer was WATCHING him. He had to do something difinitive, or be suspected himself.
From what I can tell, it looks like he was perplexed by Lois's treatment of him up to that point--they were partners, after all, and she was keeping things from him.
That whole episode was a case of crossed signals.
Lois thought Clark wanted to horn in on her story and take all the credit, but Clark was confused by everything she said along those lines because that WASN'T his intention.
He wanted to work WITH her on it, even AFTER he'd screwed up and blown her cover, but she wouldn't listen and kept berating him for the mistake he'd already admitted he'd made.
"You take turns, advise and protect one another, even heal or be healed when the going gets too tough. I know! That's not a game--that's friendship!" ~Shelly Mezzanoble,
Confessions of a Part-Time Sorceress: A Girl's Guide to the Dungeons & Dragons Game Darcy\'s Place
