Mi sono versato il caffè addosso!

I have been defined as a very pigra (lazy) and often uncoordinated person. This means that at the age of 32 I still pour drinks and food on myself with sad regularity. So, when I want to explain to people why my shirts look like the bavaglino (bib) of a 6-month-old, I have to use the adverb addosso.

The adverb addosso means “on (one’s person)” and it’s used when people, animals, and objects are located, lean, or fall on one’s person. Because it’s an adverb, it is unchangeable (it does not agree in gender or number with the person it refers to).

The Dizionario Etimologico Online explains that the word comes from dosso, an old word meaning schiena (back). This means addosso originally meant only “on one’s back.”
Let’s see a few example of how addosso is used:

Il ladro aveva addosso un cappotto marrone.
(The thief had a brown coat on himself.)

La bambina ha vomitato addosso alla zia.
(The little girl threw up on her aunt.)

L’armadio gli è caduto addosso e lo ha schiacciato.
(The armoir fell on him and crushed him.)

Il cameriere ha rovesciato la zuppa addosso a Paola.
(The waiter spilled the soup on Paola.)

Mamma, mi sono fatto la pipì addosso!
(Mom, I peed on myself!)
Notice that, if mentioned, the person on which something is located, leans, or falls, is introduced by the preposition a.

Most of the times, addosso is used in reference to people. However, you can hear it used in reference to things, especially big ones:
Ho spostato il tavolo addosso al muro.
(I moved the table against the wall.)

RELATED WORDS

addossare (tr. v.): to lean sthg on sthg.; to lay the responsibility of sthg. on s.o.: Mi ha addossato tutta la colpa, She/He laid all the blame on me.