You can do almost anything *IF* you work at it hard enough.
Check the first page of the big holyshit/downshit thread for a list of common variables you can use in your if statement.
something like this might be a way:
/if (${Me.Disc.ID}==0) /disc ${Select[${rand},"disc1","disc2","disc3"]}
You'll have to look up the syntax for disc , select and check for rand.
Search the wiki for TLO ( Top level object )