Putting itching powder on teachers’ seats — it sounds like something out of the Our Gang comedies, or Booth Tarkington’s Penrod. Well, things have changed, buddy — when the Shoe Bomber tried to give himself a hotfoot, we sent him away for life! And when somebody, presumably students, pulled this at East New York’s P.S. 345 yesterday, the Department of Environmental Protection sent a frickin’ hazmat squad and teachers went through a Silkwood decontamination shower. “Somebody could have killed me,” a teacher tells the Daily News. “I feel it personally, because I have so many allergies.” So far the enviro squads haven’t found anything evidence of terrorism. Witnesses say the stuff looks like fiberglass, so it is probably not mucuna pruriens or one of the other traditional components of itching powder. But when these teachers find out that the whole purpose of itching powder is to cause contact dermatitis, you’ll need a collating machine to sort out the lawsuits.