“What is this ‘Technical Debt’ of which you speak?”

As we start updating a number of web apps running on some older libraries, I was asked the above by a non-programmer.

Best analogy I could think of:

Technical Debt.
The nerd equivalent of some rather dodgy sushi for lunch… particularly notable for the relief when it is finally and violently purged after a period of mounting apprehension that something very bad could happen soon.