1
general::
Phrase(s): pitch something into something [and] pitch something in
to toss or throw something into something. • Please pitch your aluminum cans into this container. • She pitched in the can.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Attack, assault, either physically or verbally. For example, Aunt Sally pitched into Uncle Rob when he forgot to go to the bank. [Colloquial; first half of 1800s] pitch on Also, pitch upon. Choose, decide on, as in He pitched on the ideal solution. This idiom uses pitch in the sense of "arrange or set something in order." [Early 1600s]
American Heritage Idioms