|1.||Ten items or less|
What supermarkets display when they actually mean 'Ten items or fewer'. Indeed 'ten items or less' is gramatical nonsense, has no real meaning and therefore qualifies as slang. That is 'or less' than what?
There are a significant number of shoppers who, when challenged about their (say) eleven items, carefully explain that the sign is gramatically meaningless and therefore not understood /does not conform to the English language.
Usually this is lost on checkout staff /clerks and often not understood by store management either. Indeed it is probably lost on the store-chain management as a whole who probably authorised the nonsensical signs in the first instance.
Higher-end supermarkets have been noted as correctly using the term 'ten items or fewer'.
That an item is not necessarily a singular object is another related issue.
Clerk "You shouldn't use this aisle as you have eleven items in your basket and the sign says ten items or less"
Customer "I'm sorry but your sign does not make any sense. As 'or less' is grammatical nonsense I couldn't understand it"