You can't take knives to the National Rifle Association's gun expo in Kentucky, US.
Many attending the expo found out the hard way, and were surprised to find they couldn't bring blades in the event, NY Daily News reported.
Thousands are attending the convention, which got under way on Friday, where Republican presidential nomination Donald Trump spoke.
Chairman of the advocacy groups Knife Rights said he was happy to help the the NRA, so set up a check-in tent for those with knifes.
"For whatever reason the Secret Service doesn't want knives in and we're happy to help," Ritter said.
By Friday afternoon about 3000 knives had been left at the check-in.