This Video Demonstrates the Recently Discovered, Super Secret Menus in the Early Mortal Kombat Video Games

Access to secret menus sometimes called Ed Boon or EJB menus (after co-creator Ed Boon) have finally been found. It only took 23 years... 

This wasn't discovered in the past two days, as the man in the video says, but they were still found very recently. According to Eurogamer these menus were found late last year by the folks at a website called The Cutting Room Floor as they looked through the classic game's code. 

According to the video description, anyone can access this special menu on Mortak Kombat 1, 2 and 3 using these instructions:

The code is P1 Block (x times) then P2 Block (x times) then P1 Block (x times) etc...

MK1...

P1 (5), P2 (10), P1 (2), P2 (1), P1 (2), P2 (3), P1 (4)

MK2...

P1 (5), P2 (10), P1 (2), P2 (8), P1 (2)

MK3/UMK3...

P1 (5), P2 (10), P1 (3), P2 (1), P1 (2), P2 (2), P1 (3), P2 (4)

via uproxx