I don't Tumbl, so it's new to me.
I take it as an expression of an overwhelming, lustful desire to copulate and reproduce with the person in question.
While I don't have the organs in question, it gets at the kind of insane, blinding, physiological response I had to the revelation of this heretofore-unknown and incredibly attractive (to me) aspect of Darvill.
If the expression is offensive to those of you with ovaries, I'll look for a more suitable way of expressing myself. (After I listen to him sing again...)
You think, what do you want?
You think, make a decision...