Being against DUIs is not the funny part. Neither is having rules.
"No DUIs" is like elementary level expectation levels. Core values are typically lofty, inspirational ideals. No DUIs is a basic requirement for being a responsible, functioning adult.
Officially sanctioning "No DUIs" as 1 of 5 core values suggests that your program has such low expectations for team conduct that it feels the need to remind them all that No DUIs is at the core of being a Ute. It also suggests that DUIs are so common on the team that it is a significant enough problem to emblazon a reminder about it on the locker room wall.
It's funny.