meaning the person you have directed 'biatchymondo' at is either being a bitch or is simply pissing you off for no apparent reason
alan: hey dude! wanna go out tonight?? we should so hit on some hot chicks/boys maybe!
Tom(big man): man....your a freaking biatchymondo
alan: heyyy whys my computer going soo slow tom??? uhhh i cant get on to my myspace to look up hot boys!!
Tom: mate, the comps being a biatchymondo