pons as·i·no·rum 
(pŏnz ăs′ə-nôrəm)
(pŏnz ăs′ə-nôrəm)n.
A problem that severely tests the ability of an inexperienced person.
[New Latin pōns asinōrum, bridge of fools (nickname of the Fifth Proposition in the Elements of Euclid, due to its difficulty) : Latin pōns, bridge + Latin asinōrum, genitive pl. of asinus, ass, fool.]