ПОПАСТЬСЯ НА чью-либо УДОЧКУ

[popasttsa па udochku]

To be caught on someone's fishing line.

To permit oneself to be fooled; to fall for a hoax or trap; to accept a proposal, an offer, etc. made to tempt one to do something.

Cf. To swallow the bait: to rise to the fly; to be taken in; to fall into someone's trap/snare.