Comment The Ultimate Hack (Score 2) 760
According to the definitions above, a hack is something quick & simple yet has a serious impact. In some cases it's humorous. It's usually computer/engineering related.
How about Microsoft's hack to stop Windows 3.x from running on top of DR-DOS.
It must have been very easy. It had a huge impact on DR & Novell. I'm sure the guys in Redmond thought it was funny.