Figure out how to mess up another programmer's project by making a subtle, hard to find (but "harmless") "bug". (Double quotes FTW!)
Try to keep them short;
shorter ~= subtle.
#define true false
Don't actually destroy the code directly. For example, from this:
for(size_t i = 0; i < 10; ++i)
for(size_t *i = new size_t; ++i; delete i)
for(size_t i = 0; i <= 10; ++i)
Is not OK. If a language actually allows you to change
<= without changing that code "directly", then it's alright. (You know what I mean. Deleting all the code is just
Up vote the most original/creative/subtle solutions.
On Mother's Day (May 8, 2011), the most up voted answer will be chosen as the winner.