About 30 protesters stood up and chanted "we believe the women" during Bill Cosby's performance Friday night at Hamilton Place.

Less than half an hour into the 77-year-old comedian's show, members of the group stood up, unveiling T-shirts with the same message.

They chanted and blew rape whistles as they were escorted out by security and police, disrupting but failing to shut down Cosby's controversial performance.

"We believe Cosby," an audience member shouted in return.

"Go believe outside!" said another.

Almost immediately after, another man began yelling, "you arrogant piece of s***, you arrogant rapist." He, too, was escorted out.

The entire protest lasted about five minutes, with Cosby urging the 1,500 fans in the crowd to remain calm. The rest of his 100-minute performance was uneventful; he delivered stories about fatherhood, motherhood, the Bible and his childhood. Those remaining in the audience evidently enjoyed the show, giving Cosby several rounds of loud applause.

Outside Hamilton Place, about 150 placard-waving demonstrators greeted ticket holders and passing vehicles on the Main Street sidewalk. The outdoor protest was organized by the Woman Abuse Working Group, an umbrella organization representing several groups including the Sexual Assault Centre (Hamilton and Area).

Retired Hamilton teacher John Paul Morrison said he's disgusted to see Cosby acting as if it's business as usual when so many women's lives have been affected by assault. He had one message for people upset about the in-show protest.

"Compared to the mental anguish of these survivors, your inconvenience is a small price to pay."

A counter-protest across the street saw a handful of "men's rights" activists decrying what they saw as "lynch-mob justice."

Wearing his signature "Hello Friend" sweatshirt, Cosby opened the show with a nod to those outside, commending their resolve in temperatures that felt like -17 C with the wind chill.

"What we can do for what we believe in, it's just fantastic," he said, after opening with a joke about the weather.

Security was tight with police visible inside and outside Hamilton Place.

Cosby's performance was preceded by announcements telling the audience to "stay calm" if disruptions occur. Cameras and digital photography were prohibited inside the theatre.

After their ejection, the jubilant protesters converged on the nearby Anchor Bar for a celebratory drink.

Ellen Newman came from Brampton to join the protest. She says it had special meaning to say out loud that she supports the women - she was once in the position herself of having to put her word against her assailant's after a sexual assault.

"I thought I was going to be really freaked out," she said, wearing a huge smile. "At one point, there were six or seven police officers right beside me.

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"Before the show, one of the gentlemen in my aisle had said, 'I hope whoever protests, the cops knock them down and hoof them in the back a couple times .' I wish I had an opportunity to say to that gentleman, 'thanks for the sentiment.'"

Protest organizer Anne Bokma said every detail of the protest had been planned well in advance, from hiding folded up signage in their boots to bringing in unwanted coats they could leave in their seats after revealing their T-shirts.

"We went in with our t-shirts turned inside out and changed in the bathroom," she said. "I am proud of Hamilton tonight."

Up to 30 women have now come forward to accuse the comedian of sexual assault. Despite calls to cancel the Hamilton Place show, operator Global Spectrum said it was legally bound to proceed unless the performer himself cancelled. Many people who purchased tickets before the allegations arose say they were denied refunds.

The protest inside Hamilton Place was the most raucous of Cosby's three-stop Ontario tour this week.

On Wednesday, protesters gathered outside the front doors of Kitchener's Centre in the Square and briefly attempted to block Cosby fans from entering the theatre, but there were no disruptions inside. More than 100 protesters picketed outside the Budweiser Gardens in London on Thursday but only one person inside the venue was ejected for heckling the embattled entertainer.

Cosby has been beset by some two dozen allegations of sexual abuse and misconduct over many years, all of which he denies, none of which have been proven in court. The allegations sparked outrage and calls for show cancellations in Hamilton and other venues on Cosby's current North American tour.

The three Ontario dates garnered international media attention because they are the first shows Cosby has performed since November, when many of the sexual abuse allegations began surfacing.

Early in his show, Cosby said he believed he would be back in Hamilton to perform again and that things then would be different.

"In two years when I come back, all the people outside will all be inside," he said.

When he finished, the crowd gave Cosby a standing ovation, and he thanked them for their patience.

"Two years from now, may we all be in this hall again together to celebrate the gift of laughter," he said.