"I misjudged the humour and offended them as a result. Needless to say I feel terrible about it and regret what was an error of judgement and I apologise unreservedly."
Bunting, a first-time councillor and former radio personality, will face the disciplinary hearing in front of Mayor Andrew King, deputy mayor Martin Gallagher and two other elected officials on Friday.
King confirmed Hamilton City Council had received a formal complaint following the private message sent on Facebook yesterday.
"Councillor Bunting forwarded a Facebook video of a road sign which had displayed an offensive message, and which was yesterday the subject of an online news article in New Zealand media," King said in a statement.
Screenshots of the video sent by Bunting were subsequently posted on social media.
"I have met with councillor Bunting this morning and, while I note he has apologised unreservedly I have been very clear that I expect high standards of behaviour from our councillors.
"I have spoken with all councillors earlier this year about their roles in our community, whether on council business or not, and will be reinforcing this message again very strongly."
Bunting told the Herald he "absolutely hates hurting people's feelings".
He acknowledged the message was inappropriate and regretted sending it but said he felt the situation had "got a little bit out of hand".
Bunting said there was no sexual innuendo meant and his two daughters aged 19 and 16 were alarmed at some of the comments being made about him on social media.
"It still doesn't exclude the fact it was a stupid thing to do. I sent it to her to make her smile and it certainly didn't."
The council's complaints committee must convene within five days of receiving a formal complaint.
Bunting said he had no expectation of the hearing other than he would explain his actions.
"It won't be pleasant and nor should it be."
The matter will be considered under the council's code of conduct policy.
- NZN contributed to this report.