Your doorbell rings you barely get to the door before the police are knocking your door in. They hand you a search warrant and seize all of your computer gear and haul you in for questioning. Imagine your horror when they start asking you why you have been sending kiddie porn from your Internet account.
If you are running your WiFi equipment unsecured you very well could have this happen to you. Spammers and Criminals are using non-secure WiFi to send spam and download illegal content. [Techdirt]