To put yourself into a unfortunate/self-damaging situation where the blame cannot be successfully shifted onto someone else i.e. Shooting yourself in the foot
James: Nah fam, got too wasted and passed out
Phil: You've cooked your own spleen, there!
James: I know, bruv
Mike G: Did you break up with Lydia?
Marcel: Nope. Told her I loved her by accident.
Mike G: CYOS.
Reginald Poshington: Hello there old chap! How goes it?
Rogers Chestertonmastercard IV: Not so well, I'm afraid old sport. I just heard back from the Regatta Club and it seems my work to further the segregation amongst the races within my rugby club, albeit a step back into the ways of the splendour of Uncle Adolf, served as a conflict of interests and hence they have heaved me from the running to become a partner. Daddy won't be pleased at all.
Reginald: Well then, old spice! You've cooked your own spleen, haven't you?
Rogers: In deed! This is TRULY a recipe for disaster
News of the world's last headline: "We've Cooked Our Own Spleen"