I always think of it in terms of say, a pile of *****, in negative terms. i.e. Sheffield Wednesday supporters think their club is massive and I agree, it's a massive pile of ***** with lots of horrible insects flying around it. Sithi.
The majority of them have turned it into a 'joke', calling themselves MASSIVE in an attempt to get people to bite. Of course people do bite but there's a fair few Wendys that still believe they are MASSIVE and when they get ridiculed for it they pretend they were joking all along to save face.