"How's about the Theorem: There is no largest real number; 1) let x be a real number 2)define y = x+1 3) since x<x+1, x<y 4) so for every x, there is a y such that x<y 5)so there is no largest real number. Clearly here we have defined y as a non-flagged constant since it is defined in terms of an already flagged constant (x namely).
Now if you understand any of that my wife will buy you a drink. She hated the math science of variables and that probably led to her pursuits in a field outside of engineering.