On last night's show Mark incorrectly defined a Rhombus, saying that it has two parallel sides and two "pointing towards each other." He went on to say that it annoys him when people incorrectly define shapes to Jack. What Mark was talking about is actually a Trapezoid. A Rhombus is what most people refer to as a diamond.

http://en.wikipedia.org/wiki/Trapezoid

http://en.wikipedia.org/wiki/Rhombus