I like to go to supermarkets and buy the most confusing assortment of odds and ends - light globes, mouthwash, copper wire, blu-tack etc - and then give the cashier shifty looks.
Whether they think I'm up to something devious, am some kind of mental MacGyver or just plain weird this is a great way to pass the time and worry people.
If they comment on the incongruous collection and try for the laugh, protocol dictates a 'I-know-something-you-don't-know' smile be given and the items be described as being for 'Home Improvement'* even if they are made up of snail pellets, bleach, a plunger, a rubber duck and a packet of straws.
At the very least it'll give the check-out chick or chap something to tell all their friends which much exaggerating of the craziness of your eyes, the condition of your teeth and the soullessness of your hellish voice.
At the next stage you can have a whole other level of fun when your local law enforcement turns up, scowling suspicously and inquiring as to your intentions, only to find you fresh-breathed, with newly globed light fittings, a snail-free garden, recently plunged toilet, soaking your whites in bleach, making little figurines of mousies with copper wire that you prop up with blu-tack, sipping a cool drink through one of your new straws and watching your rubber ducky bob around in the bathtub.
Their embarrassment will be almost as tangible as their mild concern as they back away from your crazy castle.
Afternoon well spent *dusts off hands*
Now if National Security forces get interested however...
[The following paragraph withheld in the interest of international security]
*Oh Sin City!