"Disgraceful behavior" refers to actions or conduct that is considered shameful, unacceptable, or improper. It implies that the behavior is disrespectful, dishonorable, or brings discredit to the person or group involved. Full definition
When he played in the reserves (before the Charlton loan and before the fans disgraceful behaviour at Fulham) he was our most creative player in that team. (arsenalfcblog.com)
Nor is it going to ensure that none of its signatories ever crosses the line into regrettable or disreputable or even disgraceful behaviour. (canadianbusiness.com)
Disgraceful behaviour from some Arsenal fans. (justarsenal.com)