That's the aggro/banzai module. You can disable it altogether along with other modules or you can do it on a per-frame basis. I don't remember exactly which section of the playerframe would have it, but it is likely called "enable aggro coloring" or somesuch. I haven't used pitbull in awhile or I'd be more specific.
The "entire" module...Is it possible to just disable for player frames? Because I like it in raid frames, it lets me know ahead of time sorta when someone is going to need healing. It's like a premonition.