To lay a silent, or otherwise, fart in a shop aisle. This must be one that is putrid to the senses.
To participate in Mine Laying, one must observe the following code for perfect mine layage:
1) Find a large shop with clearly observable aisles, music shops generally are ideal.
2) Choose an aisle with no body present and release you mine.
3) Walk away from you mine and observe from a safe distance.
4) Try not to laugh too noticably when you clearly see the next person in the aisle grimace with sheer horror at the smell they have walked in to!!!!