Irrumatio simply face fucking/throat fucking (dunno about it being man on man)...i've put it in my ads for quite some time because it means face fucking/throat fucking and well i'm definitely not a dude lol.
I could never use Wikipedia when writing papers and such for a source/reference (most teachers I've had don't consider it a legitimate source since almost anyone can toy around with it) so lol I don't really look at it.  
Maybe look at the other definitions you find via google aye not on Wikipedia.