From the name of the ubiquitous host of many TechTV computer shows, to "leo laporte" is to give an over-simplified answer to a clueless newbie asking a question that they wouldn't understand the complete answer to anyway.
When my mom asked if her Mac was susceptible to viruses, I gave her a quick "leo laporte" and switched on her firewall.
The practice of leaving coded chalk marks on or near buildings or sites where a "war driver" has identified available 802.11 wireless network access. The marks usually indicate the type of access and level of security.
This practice is decended from the way hobos used to chalk mark the curbs outside homes where an easy mark could be approached for food or other handouts.
I located a particularly handy open wifi network near the ballpark, so I warchalked it for my hacker brothers and sisters.