Bears, hamsters, coffee and hashtags

All hipster bars and coffee shops these days have signs with quirky slogans or jokes on them. They come with a punchline that undercuts the set-up, and the first time you see them they are genuinely really funny. For instance, this classic 'bears' sign:

Dunno, maybe bears... 

And this one self-referencing hipsters:

Hipsters... no wait, hamsters

But after the first time, the joke is no longer funny because it has to be original. That doesn't actually matter, because it will be new to most of the people that see it for quite some time, so it's OK that some people are bored of it (it probably won't put them off going to their regular place or a cafe that looks nice).

There's something more to the joke format that I'm beginning to find wearing, though, and I think it's the Conventional Set-up --> Twist format. Even though this is essentially how jokes work, it has somehow become a cliche on blackboard coffee shop signs.

I was at the annual meeting of the Linguistics Association of Great Britain last week. I go every year, as I'm on the committee, and it's held in a university somewhere in the UK. They had this sign:

Drink responsibly!
#DontSpillIt

If this had been a normal blackboard sign, I'd have found it twee and predictable, even though I haven't seen this exact joke anywhere. The format has become wearing. But somehow, putting the punchline in a hashtag was enough for my jaded joke palate to accept this as a witty sign. A normal blackboard says "We're cleverer than you: we made you think one thing and then turned it round on you". The hashtag somehow says "The sign is real; we mean the main message literally and aren't trying to subvert it. However, look at this funny interpretation too".