next time youre fucking a girl from behind, once she gets really wet, or you can just spit on your finger, try slipping a finger in her pussy WHILE fucking her. with my ex girlfriend i couldn't do this cause she was too tight, but with my current one i can fit 4 fingers, palm up, above my dick... so thats 4 fingers plus a penis in her pussy. it feels really good.......its like sex, jerking off, and fingering a girl all in one! just make sure its wet enough to not hurt her.