In layman's terms (the wikipedia is a terrible layman's description) - a congestion game is one where a particular strategy gets less attractive the more people choose to.
Advertising spending, for example in the context of tobacco advertisements, is actually a pretty classic example of what the person you are replying to said though. You'll have to clarify what you mean by making decisions atochastically and how exactly this ends up a congestion game. If everyone else is advertising their cigarette brand, your optimal strategy is to advertise as well, which is not a congestion game. You just end up with a dominant strategy of "advertise" for a differentiated product, which means it is better for you to advertise no matter what. It can also go the other way in advertising though. For example if you sell some undifferentiated product like a commodity, no individual wants to advertise since driving demand for the commodity helps everyone in the market while you have to bear the cost.
Advertising spending, for example in the context of tobacco advertisements, is actually a pretty classic example of what the person you are replying to said though. You'll have to clarify what you mean by making decisions atochastically and how exactly this ends up a congestion game. If everyone else is advertising their cigarette brand, your optimal strategy is to advertise as well, which is not a congestion game. You just end up with a dominant strategy of "advertise" for a differentiated product, which means it is better for you to advertise no matter what. It can also go the other way in advertising though. For example if you sell some undifferentiated product like a commodity, no individual wants to advertise since driving demand for the commodity helps everyone in the market while you have to bear the cost.