If you woke up Friday to find that a waterproof cover reading "Wrap it and Ride" had mysteriously appeared on your bicycle seat, you can thank Toronto Public Health.

That's the catchphrase the city agency is using to promote its 2016 condom giveaway and safe-sex awareness campaign, which launched Friday. To advertise the slogan, thousands of volunteers fanned out across the city early Friday, putting the waterproof seat covers on bikes.

"Wrap it and ride — that's the message," Coun. Joe Mihevc, who chairs the Toronto Board of Health, told a news conference at Nathan Phillips Square Friday.

"Have fun with it. But the important thing that underlines this lighthearted message is really a serious campaign," he said.

"You don't want to get a sexually transmitted disease. There are too many in Toronto. It is the number one way in which diseases are transmitted in Toronto and that's why we're focussing so hard on this campaign."

About 2,000 volunteers fanned out across downtown Toronto Friday morning to promote the city's new condom giveaway by distributing free waterproof seat covers. (Mike Smee)

Over the course of the year, 3.8 million condoms will be available free at colleges and universities in the city as well as at some youth programs, community centres and Toronto Public Health offices.

In keeping with the "wrap it and ride" slogan, they'll also be available at some bike shops.

This year's condom wrappers say "Explore TO," with the TO taken from the now-famous Toronto sign at Nathan Phillips Square.

One of 3.8 million condoms the city will be distributing free over the course of the year. (Mike Smee)

Distributing free condoms "is an important part of the message that needs to get out there: Yes, have sex. Make sure it's safe," Mihevc said.

This is the third annual giveaway, which Mihevc said has proven effective at reducing STDs.

He said each condom cost the city 11 cents, for a total campaign cost "in the tens of thousands."