Outlook Tactical Nuclear Penguin is a beast of a speciality stout that, at an ABV of 32 per cent, is seven and a half times the strength of the wildly over-rated black stuff that Guinness churns out.

This imperial stout also retails at around £40 a bottle, so isn't really a session bevvie – not that many people could survive a skinful of this chestnut brown brew.

The beer is one of a number of frankly insane (but very tasty) craft ales and lagers that James Watt and Martin Dickie have produced since starting BrewDog as 24-year-olds in 2007.

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This Aberdeenshire-based brewery has a loyal following and fame has spread as far as the US, where the pair will soon have their own television show.

A key to their success has been convincing 7,000 discerning drinkers to invest in the business, so that two years ago BrewDog raised £2.2m through crowdsourcing to build a new brewery.

The boys are at it again, looking to increase their output 1,000 per cent by raising a record-breaking £4m through their "Equity for Punks" scheme. They also want to set up a brewing academy in London and expand their bar chain overseas.

Mr Watt and Mr Dickie are looking to turn BrewDog into an empire, which would rather take away from the niche, craft-selling point of the business that their customers so love.

Also, for £95 a pop, the 42,105 shares sold will represent just 3.6 per cent of the business. That values BrewDog at more than £100m, well over 200 times BrewDog's profit in 2012.

Sure, cannier investors will factor in the company's recent growth – an annual average of 167 per cent over the past five years – and future expansion when they buy the shares. And Mr Watt insists that the brewery has been constrained by capacity issues that the fundraising will solve, meaning the multiple will soon be closer to the 20-25 times that the industry's biggest players enjoy.

Plus, the more hardened drinkers will find that the savings they get as a shareholder means that buying a case of beer a month should see the £95 recouped within a year.

But, as things stand, investors are being offered a minuscule percentage for a lot of money. This looks like the brewers are taking advantage of their worshipful following's emotional attachment to BrewDog.

Creating such a strong brand is obviously something that Mr Watt and Mr Dickie have every right to exploit. But "Equity for Punks", like the Tactical Nuclear Penguin, should come with a warning to consume with caution.