Speak with a colleague about a time when competition arose between your team and another. What was it you were competing for? How were your feelings for your own team and your relationship with the other team affected? 

The next time you notice that the team is complaining about another department, a business partner, or a customer, you can draw up a list of the behaviors in your team that are liable to make things difficult for the other group. For example: you respond with counter-arguments instead of asking questions, choose separate tables in the lunch room, only reply to emails after reminders. 

Suggest a meeting with a representative from another team or another department and discuss how you can make things easier for one another at work. Feel free to link this to benefit to clients, members, or customers.