Any stimulation of the [[nipples]]. 

h4. Subtypes:
* [[nipple_tweak]]
* [[nipple_pull]]
* [[nipple_rub]]
* [[nipple_torture]]
* [[nipple_biting]]
* [[nipple_flick]]
* [[nipple_press]]
* [[nipple_push]]
* [[nipple_injection]]
* [[nipple_fingering]]
* [[licking_nipple]]
* [[vibrator_on_nipple]]
刺激乳头