Best source of information is likely located in the Student Code of Conduct:
http://www.mcmaster.ca/policy/Studen...tudentCode.pdf
It doesn't refer to sex on campus specifically, however having sex in public is breaking the law, therefore it would be considered a Major Offense. Pending the investigation/hearing, the possible consequences are listed in the Code.
Also, since you are breaking the law, in addition to possibly getting kicked out of McMaster, you should also be concerned about facing criminal proceedings. If convicted, you could face fines or even jail time.