Here are some sentences you could use!
1. It is rather unseemly to attempt to negotiate a drug deal in a school.
2. Let's try to negotiate a solution for this unseemly behavior.
3. My family was negotiating about what the new baby's name was going to be.
4. When I am watching a scary movie, I tend to have unseemly thoughts.
5. t was unseemly of you to act that way.
6. We negotiated and came to an agreement on how we would take turns
Chose one that you like!
Hope this helps :)