Hackers bypass, multifactor authentication schemes by sending a blizzard of spamming login attempts until the accounts owner accepts the MFA prompt out of desperation to make the spamming stop. 

CyberWire Glossary link: https://thecyberwire.com/glossary/mfa-prompt-bombing

Audio reference link: movieclips. “Sneakers (2/9) Movie Clip - Defeating the Keypad (1992) HD.” YouTube, YouTube, 29 May 2011, https://www.youtube.com/watch?v=oG5vsPJ5Tos.