To use the rubber sheet analogy, imagine Jupiter on the sheet.
it creates a dent in the sheet.
Now, roll another object on the sheet so that it "bums" against the edge of the dent made by Jupiter.

Because nature balances her books, as the small object hits that dent, it will take a tiny portion of Jupiter's momentum in the form of an acceleration. As it moves, with that acceleration from the dent- it will have been "bumped" by Jupiters gravity well.