For me it's when an extreme attractive young lady decides, of her own free will, that she want's to suck my cock. Bonus points if she deepthroats it, gags on it, lets me skeet on her face and then swallows my man-gravy. That's enjoyable and quite a boost to ones ego. I don't know of anything I'd rather do. Looking back on all the impromptu blow jobs I've gotten brings me a lot of pride.
Now just about any guy that's in a relationship can eventually talk their significant other into going down on them. No big deal. What I'm talking about is when a hot chick that you barely know is eager to put her mouth on your penis. No begging or manipulation required. Cocks are pretty disgusting. All that pubic hair and the stench of ball-sweat. Also, she has no idea how many bitches that thing has been inside of or when the last time I showered was. I think this is a great accomplishment and one that doesn't get the credit that it deserves.
What would inspire women to do this? You've pretty much gotta be either rich or extremely good looking. Now maybe she is just a super good looking slut but how often do those come around. Gentlemen, I think you should pat yourself on the back the next time this happens. Anyone who has gotten this happening give yourselves a round of applause. Also, let us give thanks to those falacio loving hotties (especially the ones with double jointed jaws).