Or alternatively: it's only a crime if you get caught.

A really big and normalized one is tax evasion in the form of paying for items or services in cash without administration. Most if not all people you can hire for jobs around the house - gardeners, cleaners, handimen, plumbers, construction, painting, etc - will take cash instead of going on record.

The challenge there is that this takes trust, because you take a risk as well / there are no assurances if they do half a job. Make sure you get an address so you can torch their house or business if they mess you about.