(Not necessarily but usually done and said in a manner involving a situation when: Semen is released in large quantities, released internally, while relieving immense stress (sexual tension), in a single load. So basically to discharge sperm very aggressively inside of your partner's vaginal region or any other orifice that can be penetrated and or injected with semen "a big cream pie".)
2) A slang for Semen, brought about by the fact that semen seems to some what resemble plain yogurt (Gurt if shortened) when spilled on certain surfaces, and or when leaking from a woman vagina or any person's skin after sexual intercourse.
1) (Guy having sex with girlfriend) "Damn it! It's too much for me to handle even pulling out. I'm gonna gurt!"
2) (random dude) "Sorry I didn't mean to shoot gurt all over your sheets."