a) Geek speak for "malfunctioning."
b) Sometimes used by the above as a euphemism for "fucking" as a derogatory adjective form.
a) "If that doesn't fix it I'll try a different drive, and if it's still malfing after that, I'll change the motherboard."
b) "...the site itself needs some work... fixed pixel height font sizes that are WAY too malfing tiny if you are 'above' the default system."
Malfing: a depraved, necrophilic, sexual act that involves digging up a freshly buried female corpse that has decayed but whose body cavity has not yet burst and setting it on a table and placing one's mouth on the vagina/vaginal/anal region whilst another jumps on the stomach of the corpse thus expelling with great force putrified organs/fluids into the mouth of the receiver to the enjoyment and pleasure for all those involved.
Receiver: Dude, will you come with me to go malfing tonight?
Jumper: Yeah, they just buried a lady 2 days ago and she should be ripe for the picking.
Receiver: Dont forget to bring your shovel and I'll bring the fold-up table.
Female corpse: Splat!