The use of initials on this board

[RHBullsFan]

ROFLMAO

IMO

Old Baldy - not an abbreviation, but may need clarification for newbies

[beastiebull]

All of those abbreviations are pretty much common sense.  If you think about them in the context that they are written the meaning will jump out.  

Maybe I'm assuming a little too much intelligence here but I've never not been able to figure any of these out.

[E.T.]

ET =  Easy Target or Entertainment Tonight(especially if you ever sat next to me during a game)

;D