Fetching details from the dictionary...
to thrust (something) into (something); to cram; to stuff; to shove
to plunge into; to charge into; to rush into; to ram into; to crash into
to delve into (a matter); to go into depth; to get to the heart (of something)
to press (someone) about; to point out (e.g. an inconsistency); to question sharply; to grill
to get involved with; to meddle in; to poke one's nose into
to riposte; to retort; to quip
ポケットに手を突き込んだ。
I thrust my hands into my pockets.
箱に物を突き込んで詰めた。
I crammed things into the box.
彼はポケットに手を突き込んでいる。
He has his hands shoved into his pockets.