- when he's smirking (see icon)
- when he's in anything but casual at-home clothing (even then, his casual clothing is subjective too)
- when he's in a maid dress especially
- when he's wearing glasses
- when he's a naked waiter
- when he's undressing
- when he's fighting
- when he's dancing
- when he's determined
- when he surprisingly takes the initiative
- probably more etc. etc...

(ha, captcha gave me: "the color of a red rice is?")