To be entirely 'macho' is an unrealistic feat for modern men and mostly doesn't exist in its purest form, no one is entirely 'macho'. Therefore, amongst most heterosexual modern men a sense of humour is taken when dealing with idealistic pressures to be 'macho'.
I.e poking fun at the idealism by acting overtly 'macho' in the knowledge that it isn't meant to be taken seriously.
He-man, the idealistic heroic macho man of 90's cartoons is no longer seen as what men aspire to be, but mocked in humour for its unrealistic idealisms.
Machoism, by my definition, sums up a type of humour amongst heterosexual men who mock societal pressures to be unrealisticly macho and unrealistically politically correct.
Machoistic humour is used when straight Men are attacked by either sex for being gay if they like something feminine.
"I'm not gay, I'm as straight as action man"