Not a completely uncommon problem with electric guitars. I have a bit more trouble with it than some due to a sunken living room with a concrete floor with a thick carpet where my amps are. It has been at times a popular discussion on the Tele and Strat sister forums. Generally caused by poor ground connections or needed cavity shielding. Usually the pickguard is the offending item. Many clever solutions I have read there. Rough up the back of the guard, pop a dryer sheet under the guard, shielding paint the cavity or line the cavity with shielding material. Both my Chinese Gretsch Jets exhibited this behavior, particularly if your hand went across the access cover on the back where the pots are located. Temporary solution, just wipe the problem area, often the pickguard with a dryer sheet. My solution, I just cover the back of the offending area with adhesive backed thin copper foil if I’m not going to attempt to track down ground issues. My EC Strat was horrible with the static, I covered the back of the pickguard with foil and 3 or so years later, still not a peep out of the pickguard The new Jet, perfectly quiet now.