Drooling/spitting on purpose

Hi I'm the mom of a happy, cuddly, active and very stubborn and sometimes naughty 14.5 month old named Teun. Recently he has discovered that it's fun to spit drool om purpose to get a reaction. It started as a way to let me know he was done eating. He now does it after I say no or just to get attention. I'm so unsure what the best approach is here. If I say no he just laughs and does it again. But if I ignore it how will he learn it's not allowed? Does anyone have any good tips?