I've come through the expression "to be a laughing stock" to talk about a person who has done something stupid and who people laugh at because of that, and I've started to wonder about it.
First of all, why do we say laughing using a gerund when this is normally used in active meaning, in the sense of someone/something which creates an effect (e.g. an interesting book, a cutting remark, a boring person, etc)? It would make more sense to say laughed, as the past participle is frequently used in passive mode, thus underlining that we are the object of other people's laughter.
Secondly, I've gone through the various meanings of the term "stock" (as in finance, animal raising, supply of things, food, punishment and other areas), but the only expression which seems to be partially relevant here is "stock" being used to indicate the degree to which someone is respected or liked by others, according to OED. However, the term in this meaning is indicated as uncountable.
Does anybody know what "stock" stands for and what the origin of the expression is? And let's not forget about the grammatical side to the question, please...