Did you know that stimulation of the male prostate induces production of semen?
The result of this is a much larger cum shot with a denser and darker consistency.
Asides from this, the resulting orgasm is much more intense.
So, imagine how guys feel after Rei and Madoka are done exploring their asses.
There is nothing greater than seeing two pure beauties become anal slaves and wrap their tongues around a gaping sphincter.