Subject: Coffee / Correction Fluid demonstration -- what is going on?

I have seen a demonstration of chemical incompatibility using a 
Styrofoam(R) cup, hot coffee, and white correction fluid. The 1,1,1 
TCA (I am assuming) in the fluid will eventually dissolve through the 
cup, but never so fast as when poured into a cup already filled with 
coffee. I was told that it illustrated a combined effect of caffeine 
and a solvent in the correction fluid.

I have a need for demonstrations of chemical incompatibility, 
especially those of such very common office items. However, I would 
like to know what is really happening here. Is it temperature? Is it 
that insoluble solvents are attacking a smaller area (of monomolecular 
thickness)? Is it caffeine? Is it something else in coffee? Is it that 
styrene is selective against aqueous solutions so that the coffee 
"pushes" the solvent into the cup wall?

Have you heard of this demonstration? Is it hooey?  

Re: Coffee / Correction Fluid demonstration -- what is going on?