I read the Crime Log compiled by the Mission Police Station to scare myself, I guess. Reports on drug arrests, assaults, weapons and the like. And then there's this one:

Assault with Caustic Chemical
August 1, 12:30 a.m., 400 blk. of Treat
Police responded to this location where one of the tenants drilled a hole in his ceiling and shoved a ten-foot pipe through his ceiling. The upstairs neighbor saw the pipe coming through his floor and he grabbed it and pulled it out of his floor. Suddenly he sees another pipe coming through the floor as the downstairs neighbor tries to gore the victim with the pipe. The upstairs neighbor managed to wrestle the pipe away from the downstairs neighbor through the hole on the floor. The victim noticed a strong smell and discovered the suspect was dispersing some sort of chemicals through the hole in his floor. The suspect would not surrender to police voluntarily so the S.F.P.D.’s Tactical Unit arrived and conducted a forced entry and the suspect was taken into custody without incident. The suspect was booked on numerous charges including Assault with Caustic Chemicals.