when you spit on your on the other persons genitals, mouth or anus to provide lubrication
i gave her a courtesy spit her pounine wouldn't burn up.
Before having intercourse, if your partner's vagina is a little to tight, you can take a light amount of saliva and lube the tip of your penis with it. This will allow easier and smoother insertion of the penis.
Your pussy is too tight, let me throw some courtesy spit on my dick.