To spit or swallow after oral sex is actually a false choice, since these are not the only two options. In fact most girls (gay men as well) choose to swallow, or do not allow the man to come in their mouth at all. Very few intentionally take a load in the mouth only to spit it back out.
When using the word spit it means that you spit out the boys semen when it has filled your mouth. To swallow means to drink the semen. Swallow also means that you suck on boys dicks and you let their penis go deep into your throat.
Do you spit or swallow hooker? I spit if it tastes like shit and swallows if its good.