The nozzle on your can of spray paint is clogged up? Don't throw it away yet.
Soak it overnight in solvent. Then use a needle or thin wire, like that inside the tie-wraps, to poke through the holes. Then spray some oil through it by using a spray can like WD-40, if the tips are compatible.
If you are using the spray paint for a lot of little touch-ups and you are worried about running out of propellant if you turn it up-side-down to spray it clear after each use, just jump it over to a can of WD-40 after each job.
Whether cleaning the tip or maintaining the tip with this technique, you can leave it for a long period of time and it will not block up. However, you must spray the new paint through the tip long enough into a garbage can or scrap wall to be sure that all the oil is gone before trying to continue with your job. Don't try this with lacquer as you cannot clean out the oil well enough to avoid fish-eyes in the final finish.