Wowzers.
Logan Paul just found out that his unopened set of first edition Pokémon cards -- which he shelled out $3.5 MILLION to get -- is a big, fat phony ... revealing the box was full of useless G.I. Joe cards.
Rumors had been swirling about LP's purchase for weeks ... with experts skeptical about the authenticity of the cards inside the box.
26-year-old Paul and his friend/famous card collector Bolillo Lajan San met with the Baseball Card Exchange in Chicago in hopes of proving once and for all that his purchase was a good investment .