Plugging any lead into an instrument while the amplifier is turned up can make horrible noises. But have you ever wondered why plugging a lead into an acoustic guitar (or an effect pedal) can make massively loud crackling noises compared to plugging a lead into a keyboard?
That's down to how they're using the barrel of the jack to switch the battery on for the guitar's pre-amplifier (the same with switching power in an effect pedal). They're running the battery power through the metalwork of the jack's sleeve, rather than having an insulated switch mechanically moved by a jack being plugged into the socket.
You're getting (typically) 9 volts of battery voltage into the sound system (which is a lot stronger than the audio signal). Compare that with plugging a jack into a keyboard, where the tip of the socket just hits a ground pin on the way in (you may get a hum, and a much quieter pop).
If you're designing an effect pedal, or fitting sockets into acoustic guitars, use a switched jack (where the switch contacts are isolated from the jack contacts), and use the switch to connect the power from batteries to the circuitry.
As a user, about all you can do is: Keep your jacks clean, so that they make a good connection (they end up on the floor and pick up crap). Simply wipe them every now and then, and sometimes scrape them around in a socket to grind off any muck. And push the jack firmly all the way into the socket, quickly. I see people just push them in until they feel a click, not realising they've only plugged it in part way.
Also there's another issue, metal fatigue in the cable. After a lot of manipulation, the wiring can break, and leads do need replacing (or their plugs need replacing or refitting to the cable). If you coil cables properly, don't tread on them or haul them around as if they were rope, they last a lot longer.