Many times when people wear a funny T shirt they normally have a funny quote or a saying on the T shirt rather than a picture. Although it is now common to wear a funny T shirt, that has a funny picture on the garment itself. But the most popular T shirts are the ones that have a funny quote or a saying in simple letters.
The reason that funny quotes are more popular than funny picture is that everyone can read simple funny sayings rather than people trying to look at a funny picture and trying to work out what that picture stands for or what it's actually trying to say. Once people have read the funny quotes then they will make their minds up to either laugh out loud, or to keep the joke to themselves.
Even at work when people have none uniform days in participating or affiliating with a charity wear staff pay a nominal fee for one day to wear normal dress down days rather than office clothes. Even on this particular day a lot of the staff would wear a comical T shirt that would have a funny quote or a saying just to grab the next person's attention.
A lot of adults especially adults with younger children between the ages of ten to nineteen, would wear a funny T shirt at the weekends. Adults normally would wear a hilarious T shirt for a number of reasons, sometime adults wear funny T shirts to embarrass their children, and reason number two would be to make them cool and hip like their younger children.
If people on a weekend go out on a night out with their friends and family, then women would get dressed up smartly, however the men would wear something less formal more casual like jeans, shoes and a T shirts. More than likely that the T shirt would have a funny saying, or funny quote. Men do this a lot just to get everyone talking and breaking the silence at a party where there would be a lot strange faces about.