voluntarily produce an error with DBCC CheckDb
Would anyone know how I can make DBCC CheckDB produce an error?


Use the lethal dbcc writepage ({'dbname' | dbid}, fileid, pageid, offset, length, data [, directORbufferpool]) ON a TEST (NON-PROD) fully sandbox environment.


  The purposes of DBCC WRITEPAGE are:
  
  
  To allow automated testing of DBCC CHECKDB and repair by the SQL Server team.
  To engineer corruptions for demos and testing.
  To allow for last-ditch disaster recovery by manually editing a live, corrupt database.
  


Apart from "The Guru" Paul Randal, @SteveStedman has a good series of Database Corruption Challenge (with solution - but refer it later once you try to address it by yourself).