inconvenient breasts
Opposite of convenient breasts.
When breasts are so large that they get in the way by getting stuck, ruining clothes, knocking things over, impeding line of sight, or even accidentally whacking someone on the head. Apparently there can be too much of a good thing.
This tag can also apply to breasts being too small if smaller sizes are a detriment in some scenario. Please do not confuse with breast envy.