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1 definition by Marc Quenneville

An erection that occurs in the morning and is naturally caused as the brains enters the REM-deep sleep phase. At this stage, the body's skeletal muscle structure relaxes and causes hypervasodilation in the capillaries of the body, resulting in said erection.
"Scott, this morning I had a huge breakfast boner and my first piss of the day ended up all over the walls"
by Marc Quenneville May 04, 2009