An attempt by one to, unwarrantedly, contribute to a personal joke, conversation or otherwise. Most commonly associated to those seeking to gain popularity with relative groups through association.
Group A(Persona1): Dude, doosh, you're making so much noise!
Group A(Persona2): Don't you mean, 'shoosh'? Haha.
Group A(Persona1): Haha, whoops. Oh well, that can be our thing.
(Person from group B overhears)
Group B(Persona1): Hey dude, 'doosh!' Haha.
Group A(Persona1): You're so climbing into Doosh; that's between me and Jeremy.
Group A (Persona1): I LOVE Fort Minor - Mike Shinoda is a genius.
Group A (Persona2): Me too. Lots of great songs.
Group B (Persona1): Oh ya! How about those instruments? (Originally uninvolved in the conversation and not a Fort Minor fan as such)
Group A (Persona1): Sounds like a bit of climbing in over there.