In
Super Smash Bros. Brawl, or any Smash Bros. game, there comes a point where a Smasher can't smash at their best. Your moves become stiff and your
reaction time decreases.
(Derived from the term 'Writer's Block', where a writer comes to a point where the mind boggles and cannot create any ideas for his/her stories)
Similar
definitions: brawler's block, fighter's block, cock block