University spokesman Costa Maragos and students union president Devon Peters both confirm in emails that the probe stems from claims that were made on Twitter that allege the host made rape jokes during a trivia night at The Owl on Thursday.
The Twitter posts also allege the host threw a chair when patrons objected to the jokes.
The university says in a statement released on Friday that it has not received any formal complaints, but that campus security is working with the students union to investigate the allegations at the the union-operated pub.
Peters says the students union began investigating Friday morning after spotting the Twitter posts.
Both the university and the students union are asking witnesses or anyone with information about the allegations to contact campus security.
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