When you perform an Eiffel Tower (that is, double-teaming a girl and high-fiving your partner in grime with both hands) on top of the actual Eiffel Tower, in Paris, France. You can also perform the procedure beneath the tower, but that is not an official Eiffel Tower Squared. This act is to the Mile High Club what Cooperstown is to the Podunk Community Hall of Local Heroes.
Ah, monsieur! You completed ze Eiffel Tower Squared! C'est fantastique! How did you do zis with so many policemen and les touristes around? Sacre bleu!