expression, godan verb (-ru)
jump at the chance; accept an offer; show interest in
Used when someone eagerly takes up a proposal, invitation, or suggestion. Often implies a quick, positive response to an opportunity.
彼はその儲け話にすぐ乗った。
He immediately jumped at that money-making scheme.
面白そうな企画だったので、話に乗
Since it sounded like an interesting project, I decided to take them up on it.