Tom Foolery... caution for the uninitiated.

It is also the Cockney rhyming slang for jewellery. Like most rhyming slang it then gets shortened to Tom

One of those opening statement posts, rather than a question. A word of caution though, for those who might attempt a little Dick Van Dyck if in London. Tomfoolery does indeed mean jewellery, and is often shortened to tom, as in "that's a nice bit of old tom she's got round her neck". However, also shortened to tom is the far less pleasant piece of Cockney rhyming slang, a "tom tit", meaning a bowel movement, except a tad more pithily expressed (excuse the unfortunate phrase). So the moral is, be cautious when in the East End of London.