The un-necessary challenge

I've been given £25 of Amazon vouchers and I'd like to put these towards buying something on my bike (am happy to pay a bit more than this).

I'd quite like - given I'm not really paying as it were and have nothing particular that I need - to buy something which in a normal day would be absolutely ridiculous and something I could never justify spending money on. Something a bit amusing, but not twattish, if you know what I mean. I don't mind if it's quite funny.

For example, I saw some carbon fibre inner tube caps (seriously). Clearly, you'd have to be a bit sad to actually buy these on a day-to-day basis, but for £15, it's an amusing purchase.

Is there anything I could get for £25 (or maybe a bit more) which you think might qualify for this? As I said, the rules are:

Must be less than £40
Must actually have a good practical use (e.g. wouldn't want to get furry dice or anything stupid)
Must be a bit bling/unnecessary/OTT