From the story of Peter Pan an thimble is a "kiss". This is a great gift for your significant other. The card the keychain come on says "My 'kiss' for you! From the story of Peter Pan". An additional excerpt from the story is also included with each keychain, (see below.)
Here is the sweet story about the acorn from the story of Peter Pan:
"She also said she would give him a kiss if he liked, but Peter did not know what she meant, and he held out his hand expectantly.
'Surely you know what a kiss is?' she asked, aghast.
'I shall know when you give it to me,' he replied stiffly, and not to hurt his feeling she gave him a thimble.
'Now,' said he, 'shall I give you a kiss?' and she replied with a slight primness, 'If you please.'
She made herself rather cheap by inclining her face toward him, but he merely dropped an acorn button into her hand, so she slowly returned her face to where it had been before, and said nicely that she would wear his kiss on the chain around her neck.
It was lucky that she did put it on that chain, for it was afterwards to save her life."
(Peter Pan, 1911, J.M.Barrie)