An Irishman, by the name of O’Malley proposed to his girl on St. Patrick’s Day and gave her a ring with a synthetic diamond. The excited young lass showed it to her father, a jeweler. He took one look at it and saw it wasn’t real. The young lass, on learning it was a fake, returned it to her future husband, protesting vehemently about his cheapness.
“It was in honour of St. Patrick’s Day,” he smiled. “I gave you a sham-rock.”