It is almost certainly an abbreviation of breakfast, as you suggested. I can't think of anything else that it could mean, although as always it would help if you gave the context in which you have encountered it.
Thank you guys!
The context confirms that it's an abbreviation for breakfast because I've heard this word in the movie of Garfield and he is about to have his breakfast and says: Uhmm, uhmm brekkie. But I wasn't sure if it could mean something like yummy or related to the food. There is no doubt.
Aboard the Starship Enterprise, they have a trekkie brekkie, before beaming down to make a rekkie of some drekkie new planet. (un reconocimiento de algún que otro nuevo planeta de mierda)
By the way, the author of "Garfield", Jim Davis, is from Indiana, USA.