Tumescence
Tumescence is the quality or state of being tumescent or swollen. Tumescence usually refers to the normal engorgement with blood (vascular congestion) of the erectile tissues, marking sexual excitation, and possible readiness for sexual activity.
This is not just an issue with males (creating erections/boners) but also females.
The corpora cavernosum ('cavernous bodies') do not just inflate in males (externally: in their penis), but also in women (internally: along the walls of their vagina); women also have vestibular bulbs in between their vaginas and their corpora.
The swelling of these when women are horny for Chad makes women's vaginas tighter and makes average penis feel like large penis and a small penis feel like a normal sized penis.
This means that Chad gets to fuck tighter pussies (and his penis will feel larger), because women's horniness for Chad allows them to emulate virginal tightness.