You try such a stunt at any major sporting event in the USA and every sports commentator will denounce you and the ACLU would be after your rear end in no time flat. Now you know why Europeans think sports fans at American sporting venues are just too civilized.... 
There is a fundamental difference between American Football and European soccer crowds, American crowds do not chant and sing like soccer crowds do. The supporters of a soccer team will have a whole catalog of team songs that they will sing periodically during the game as a section of the crowd, or the whole stadium, becomes an impromptu choir. They will also chant in unison, some of the chants are extremely amusing and/or ascerbic. European soccer does not have bands and Cheerleaders to entertain them, so they entertain themselves, and provide huge encouragement for their respective teams. By comparison American Football crowds just produce "white noise" or the occaisional chant of "de-fence"
Having said that, There is no excuse for racism in any of this and should be dealt with severely.
If anyone is a monkey surely it is the Spanish surrender monkeys that fit the bill.