A person having seasoned guts is a term assigned to a woman that likes to have a guy ejaculating inside of her pussy; this is without the use of a condom. The seasoning she refers to is the man juice (cum) being excreted from his penis ☺.
Seasoned Guts:
He fills up her insides and at the end he seasoned her guts. She was so happy, tired and pleased that she went to sleep.