Be sold a pup British old-fashioned informal slang
The verb "buy" can substitute for "be sold". A "pup" is a puppy or young dog and is probably being contrasted with an animal that is older and does not need to be trained before being put to work.
If someone "is sold a pup", he/she is conned into buying something that has little worth on its supposed prospective value.
You should take into consideration when buying a high-end item. Just in case you're sold a pup.
A: "Your pair of Jordan looks cool." B: "I was sold a pup, these are not authentic. Anyway, thanks."
Consumers nowadays are more cautious about shopping in order not to be sold a pup.
The verb "be" should be conjugated according to its tense.
The expression is first recorded in 1901.
Daughter: So I really want all my friends to have a great time. I was thinking it would be a good idea to have some candy out on the tables for people to snack on.
Mother: Well, if you want them to really enjoy themselves, candy is dandy but liquor is quicker.