cc fried up that chicken, rite? well andre smelt that s*** from outside and by tha tyme i got in thurr his ass wuz all over it.
or
1: (fittin to pass tha bleez)u aint smokin no mo, playa?
2: naw, maen, u all over it.
To make an act one's top priority, much like scarfing free breakfast would be for a donkey, were it confronted by an unattended waffle. Usage of the phrase implies some amount of immediacy or urgency to the performance of the act.
An additional component often added to the commonly used all over it phrase, thus creating a simile. This helps to reinforce the point and also shows that the user of the phrase has a firm grasp of the english langauge.
When the standard phrase "Im all over that report" becomes dull..Instead it becomes "I'm all over it like a rash".
Shows the true passion and skill of the worker/user of the phrase or there could be some bull-shitting involved.