The curse put upon Urban Wave is the tricky one. It does not only turns her sometimes into big, fat, pear-shaped girl uncontrollably.  
And it does not just cause sometimes the butt and hips expansion uncontrollably.
 
Imagine that sometimes it just messes with her weight - sometimes she may be looking thin, fit in her clothes, but her perceptible weight is incredibly high! So sometimes chairs crushes under her seat, while the similar one can easily stand a BBW looking way fatter than her, leading Urban into total embarrassment.  
And its not just the only one sign of those magical accident - Adrienne during those phase of curse is leaving much deeper traces than heavies females she has ever seen and have other signs showing to the world, who is the heavy mare here.  
So, if you have noticed that lastly a wooden bench has been broken in the park or the concrete one had a deep hole on it, now you know who is the guilty for this.
 
Sometimes there are bronies or furries with fat OCs weighting like a feather. So why not to do the opposite?