object of fantasy during masturbation

desire, lust, greed

fill up / satisfy, meet (a requirement)

to use / to employ / to make use of, to apply / to spend

oneself / first-person pronoun: I, me (often shows the speaker's lower position in a hierarchy than the addressee) / (Kansai) you

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

to use one's head

use one thing for many purposes / work someone hard