Go into Argos, buy something really cheap and leave. Wait (possible several days) for the ticketing system to wrap round (it's only 3 digits) and go and claim an (almost certainly) more expensive item with the same number (they never check the description, which is in a much smaller font). For bonus points, have a friend get the duplicate ticket and walk off with 2 of the expensive item after the friend complains that his never arrived.
Get a transmitter that triggers those resonance scanners that shops have at the exits (or just stick a tag on one, if you can). Wait for them to get so upset that they turn them off. (they are pretty much the only security in most shops). For bonus points get a transmitter powerful enough to trigger a whole shopping center.
Something that I really should have known before:
for x in `cat file`
... will tokenise file but
cat file | while read x
... will do line-by-line processing, which is often what you actually want.