New York State's decision to crack down on bagel vendors who weren't charging an 8.875% sales tax on sliced bagels
Belt Buckles: In Texas, your belt isn't subject to sales tax, but that belt buckle sure is.
Cup Lids: The state of Colorado recently decided that lids for disposable drink cups are non-essential food packaging and therefore not exempt from sales tax.
Haunted Houses: While movie theater, Broadway and concert tickets are not subject to NY State sales tax, admissions to haunted houses are.
Tethered Hot-Air Balloon Rides: Kansas has decided that an untethered hot-air balloon is carrying passengers and therefore qualifies as a sales-tax-exempt form of air transportation. But if it's just a balloon that never comes off its tether, then it's an amusement ride and subject to sales tax.