The “icing on the cake” is an idiom that carries at least two well-known, related meanings. It means that a positive or negative situation has been made either more positive or nore negative by the addition of another factor. A positive situation, for example, might be enhanced by a second good thing, making it even better. Like many idiomatic expressions, the true meaning behind the phrase is more easily discerned by considering the context in which the idiom is said or written.
Perhaps the positive meaning of “icing on the cake” is the more commonly used one. A person uses this saying when he already has something good, but another good thing comes along to make the first thing even better. Often, the “something good” is a situation, though it can refer to tangible objects, too. For example, if a newly married couple finds an apartment for rent within their budget, this is something good. If that apartment is equipped with a private washer and dryer for laundry, this makes it even better.
Somewhere along the way, the positive meaning behind this phrase morphed into a negative, sarcastic one. Similar to the positive version, a person uses this negative version when he already has something bad, but another bad thing comes along to make the situation worse than it already was. Also similar to the positive version, the “something bad” can be a situation or a tangible object. For example, if the same newly married couple in the affordable apartment with the private washer and dryer find out their apartment has a termite infestation, this is something bad. If they discover their private washer and dryer increase their water and electric bills higher than is affordable, this is the icing on the cake.
Typically, this negative version of the expression is used in an ironic way. The speaker or writer doesn’t actually want the listener or reader to think good things are being coupled with more good things. Rather, he’s using sarcasm to convey the opposite is the actual situation.
These days, people use this phrase in a variety of ways. For example, it’s not uncommon for bakery shops to use the saying to name their businesses, which is a quite obvious use of the expression. Other businesses, such as event organizers, use the expression as their business name in a more subtle way. The idea is that two good things are coming together with the help of that business’s services.