There once was a mother potato who was very protective and strict with her three potato daughters but the time came when she felt she should discuss marriage with them.

Mother: "When you grow up, who do you each want to marry?"
1st Daughter: "When I grow up I want to marry a Duke of York potato."
Mother: "Very commendable, dear."
2nd Daughter: "When I grow up I want to marry a King Edward potato."
Mother: "Ah, such excellent taste, dear."
3rd Daughter: "When I grow up I want to marry Des Lynan."
Mother: "No, I forbid it!"
3rd Daughter: (shocked) "Why's that?"

Mother: "He's only a common 'tator!" [commentator]

My apologies for this one being quite awful ...