When my friend had a birthday problem, he came up with a brilliant marketing solution.

Every year, he would send out invitations to his birthday party … and would get annoyed with the way people would procrastinate about replying.

So, one year, he mentioned in his invitation that he was setting a strict limit of 50 guests – first come, first served.

That year, he was quickly flooded with replies.

The moment he attached scarcity to his birthday ‘product’, more people wanted it.