Married guy here. If the guy sucking me was smaller hung and he started licking my asshole, I'd probably go into femme mode and ask him to slowly fuck my ass. Normally a top here, but if you're a man with a smaller penis, I tend to want it in my butt.
a BKB62 :Right on, if a man will let you lick his tight sweaty asshole when giving him total oral service then more than likely he'll let you slip a thick finger fully into his asshole to massage his prostate and have him howl from a strong orgasm as his asshole cums around the finger and his load his even bigger than if the finger wasn't in the asshole massaging the prostate to maximal orgasmic pleasure.