We can imagine many chicks would get nervous when their man heads out the door to get pissed with the boys before the big wedding day.
A typical stag night usually includes a lot of partying, alcohol, strippers, and often some people you may be attracted to.
One chick wanted to make sure that if she couldn't be there, she would still fend off any other girl that may look at her bloke. So, she made him a t-shirt.
Most can see the funny side but if you think that's stage 5 clinger, you haven't met Jane yet...