Something similar to this will get the job done:

RewriteEngine On
RewriteRule ^events/([^/]*)$ /events?pg=$1 [L]

How it is doing is:

  1. Activating the Rewrite engine
  2. Matching any request which has the shape occasions/something
  3. Storing the 'something' (the brackets indicate the match ought to be saved)
  4. Redirecting towards the ugly form while using saved variable.
  5. Stopping any more rules from being applied ([L])

Hope this can help.