They also sell a clear primer.
DO not skip the primmer.
It's purple so the inspector can see it was done correctly.
Really want to save 30 sec. and have a fitting come undone and flood the house.
A friend was building his own house about 24 years ago and didn't use the primer. The inspector made him redo all the fittings. A time-consuming and expensive effort since the fittings couldn't be reused. The pipe was salvageable for the most part.
Lay down a rag below the area you're working in. You don't need to slop on the primer, just go slow until you get the touch. Find out if local code requires a colored primer for the inspection, but you won't want to drip it in any case.