A run on sentence is a sentence which should either be two sentences, have a conjunction added to make the usage grammatical, or be punctuated correctly. The main problem with run on sentences is that even if their meaning is clear, the syntax is going to be wrong. More likely is the fact that mixing the two sentences will cause some confusion regarding meaning and context. The result is usually a mess.
Examples of Run on Sentences:
|I'm going to the museum George ring the taxidermist.|
What a wonderful fish are you married?
Life is what you make it about 182cm, red hair and charming.