Incidentally, clock faces are often set to 10:10 when on display as it bears a resemblance to a smiling human face. Triggering our innate response to feel positive emotions towards that... ...clock.
Anyway, if 10:10 is strap-on time, that might well be why the clock is smiling, after all.
There was a time when it was mandatory to have "rule" written in the title in any way possible. That era and the reason for it are long gone, but the tradition remained.
Wordplay with (to) strap on and strap-on which is a device (most commonly a dildo) attached to a person's (most commonly a woman's) groin to simulate penile stimulation for their partner