As a noun:
* The con artist tried to dupe the elderly woman out of her savings.
* The website was full of dupes – fake designer handbags at bargain prices.
* He was a dupe for believing their lies.
As a verb:
* They duped her into signing a contract she didn't understand.
* The scammer tried to dupe people into giving them their credit card information.
* Don't let them dupe you with their promises of easy money.
Informal:
* "I was totally duped by that fake online store!"
* "He's such a dupe, he believes everything he reads online."
It's important to note that "dupe" often has a negative connotation, implying someone is being tricked or manipulated.