Accollarsi, is a reflexive verb, meaning to take on a burden. I imagine that it stems from the word collo, or neck, which is where one bears a burden. Just like many Italian words, there’s a standard meaning, and then the slang colloquial meaning (still not sure if it’s strictly a Roman thing).
Literally, to burden oneself with something, or to take on a responsibility. When used today, it can mean to burden oneself with a heavy bag, but also mean, you are burdening yourself with someone else’s presence. Ouch, I know. For example:
-“Ieri sera siamo andati a ballare e mio fratello più piccolo ci si é accollato” – Last night we went out dancing and my little brother attached himself to us.
Used primarily by youngsters, and maybe only youngsters in Rome, accollarsi also means to be ‘down for‘ something, or to be ‘OK with‘ plans. For example:
-“Andiamo all’Angelo Mai stasera?” – Shall we go to Angelo Mai tonight?
– “Sì sì, me l’accollo.” – Yea sure, I’m down.
Keep in mind that accollarsi has to be conjugated in the sentence, and conjugated as a reflexive verb according to tense and person.
So if someone asks, “Hey Zvia, are you going to see Digitalism play at Circolo degli Artisti on April 3rd?” My answer will most definitely be, “Che figo! Sì, me l’accollo! Daje!”