Note to potential D.C. Council witnesses: Best not to diss councilmembers ahead of your testimony. Especially in writing.

Just ask Robert Cane.

Yesterday, the executive director of Friends of Choice in Public Education was among dozens of charter school advocates who showed up at a council budget hearing to plead for a restoration of facilities funding for charters cut in the mayor’s proposal.

After Cane completed his testimony, Council Chairman Vincent C. Gray had a couple of questions. He produced an e-mail Cane had sent out to several charter groups ahead of the hearing before Gray, long a critic of certain charter-school practices.

The e-mail, which contained instructions for hearing witnesses, contained this line: “You may be asked policy questions after your testimony. Please understand that these questions are a trap for the unwary, especially if directed at you by [Tommy] Wells, Gray, or [David] Catania. Please do not answer unless you are confident that you have absorbed the talking points we’ve previously distributed to you.”

That led to this exchange (watch it, forward to 2:32:50):

Starts Gray: “I’d love to hear you explanation of it.”

“We always encourage the charter school leaders…not to talk about polict as ooposed to their own schools. It’s because you’re very smart, and you are hard-charging, and if they say anything at all, they’re…gonna put their foot in their mouth even more than I have done,” Cane replied.

“I really think you put your foot in your mouth.”

“I just said I did….I apologize, Mr. Gray.”

“Well, I appreciate that.”

“It was bad judgment and I apologize…”

“I find it reprehensible, gratuitous…”

“Well, I think it was bad judgment and i apologize. I think that reprehensible is too strong…I’m sorry….”

“Can I finish?”

“A lot of people who got this [e-mail] will never hear this dialog, unfortunately. So let me tell you what I’d like you to do.”

“I will.”

“I’d like you to send out another e-mail to the same group of people, and say exactly what you just said.”

“Happy to do so.”