Fresh hot sperm.
After I ejaculated on my girlfriends face, I tried to push some of it into her mouth with my fingers. She stopped me; explaining, "I prefer my 'wiener gravy' hot"! She further explained, "If you want me to swallow your jizz, please cum in my mouth"!
I immediately got hard again, as this was the first time she had told me how she preferred her sperm. And since I had been hoping that she was a swallower; she really made my day as she sucked me-off and let me shoot my second load of "wiener gravy" right down her throat!!
Ever since then, I have no problem getting hard for her, and fucking her little pussy like she wants it. Because, I know that she's going to take a hot shot at the end, and like it!!