>Ethically and utilitarian-ly speaking: [can a pope] be reckless fun, stupid\irresponsible\ etc?
Depends on your ethics and how chaos unravels. If, for a more extreme example, you are reckless and drive a vehicle under heavy influence of drugs in an abandoned ghost town, you will probably only risk harming yourself, but if you do it near a populated area, you could pointlessly kill or seriously injure a bystander with your recklessness. Most ethical models and especially utilitarianism denounce that.
Some ethical models even declare you have an obligation not to harm yourself, especially if you have dependents. You are a part of a society, your situation affects others. So if you are negligent in your winter rainy stroll and that gives you hypothermia and you contract a disease in your weakened state, how will that affect others? Similarly, if your KFC diet isn't carefully chosen, you could deprive yourself of vital nutrients and contract an easily avoidable disease. How will that affect others?
But!
Most of your ideas of reckless fun are wholesome fun, which as low or no major risks to other people. Changing your appearance with shaving and tattoos is fine under utilitarianism and most ethics (assuming your tattoos aren't a threat, like gang or nazi symbols). Anyone who doesn't like the look is a baby and their discomfort is trivial, cancelled out by those who appreciate and enjoy it. You have every 👻right👻 to have that fun! Eating KFC for a week is a fun challenge and as long as your menu options are diverse, you can at least get essential vitamins and minerals through fruit juice, vegetables, protein-bases and grains. It's not healthy, I don't recommend doing a whole week unless you have a cheat snack of healthy foods you're missing, but you can do this challenge with minimal self-damage and in that case it's unlikely to have a notable affect on others.
Note!
I have taken a stricter approach to ethics and utilitarianism in this post for the sake of discussion - I do not constantly uphold myself to always do the utilitarian action, and I do not expect you to either. It's acceptable to do occasional or slightly 👻bad👻 things, that's life, that's human, and none of the examples you've mentioned are likely to be harming yourself much, or harming others much. And if you are diagnosed with an imminently-terminal disease, then obviously minor self-harm like eating more unhealthy foods will be more acceptable as long-term health is no longer a concern.
As for appropriating symbols of worship, that's very very common. Just ask the Romans where their Gods came from. See also: https://en.wikipedia.org/wiki/Flood_myth
<> by the way, the flag in the background is not a jewish item. the mad lad has taken symbols without understanding them - a dangerous game.
