The Gentleman's Rule, sometimes called the Gentleman's Clause, is a ruling in some professional tournaments for the Super Smash Bros. games. An addition to Dave's Stupid Rule, the Gentleman's Rule states that any stage can be played on, provided both players consent to the stage's use. Assuming this is the case, Dave's Stupid Rule is overrided, potentially allowing for players to use counterpick stages that they have already used, as well as banned stages; the Gentleman's Rule can also be invoked to skip the process of stage striking.
The rule is most commonly invoked in cases of sandbagging, where higher-skilled players might allow their opponent to choose whatever stage they desire; American smasher Mew2King is particularly well-known for this in his sandbagging matches.