In episode 14 Kanbaru answered her phone introducing herself as Araragi's love slave. She said this despite the fact that she apparently didn't know it was Araragi on the other end...in front of several children. Moments later she interprets Araragi's request for help to mean she should strip, which she then starts to do.
In episode 5, Hanekawa gives Koyomi a "ticket" that allows him to touch her boobs as much as he wants, as long as he wants. Koyomi's pretty damn happy...until Hanekawa adds that she'd hate him forever if he used it. Koyomi immediately decides that it ain't worth it.
Episode 9 of Nisemonogatari. During an attempt to 'greet' Mayoi, Koyomi is tripped by Shinobu, who then proceeds to wave mockingly as her hand disappears back into his shadow.
We find out in Nisemonogatari that Koyomi is afraid of heights by Karen carrying him around on her shoulders. It's also ridiculously cute. He even cries.
"S-s-s-s-scared! Scared! Scared! Scared! It's too high and very scary! Let me down. Let me down. Let me down now! I'm sorry! Please let me down, Karen-san! No, Karen-sama!"
In episode 10 of Nisemonogatari, while talking to him in Mr. Donut, Kaiki snatches Koyomi's wallet out of his hands and keeps the entire thing. He does not stop talking at all.