Joe Jonas is being proactive about keeping his clean-cut image in tact. 

The middle Jonas brother is slamming a report that a sex tape of him and girlfriend Blanca Eggenschwiler is floating around.  The 23-year-old, who was once known for wearing a "purity ring," is denying that there is any truth to the rumor about him and his Swiss-born model girlfriend. 

The report alleges that Joe and Blanca were drinking and smoking marijuana in the video as well.  A rep tells Us Weekly that no such tape exists, the whole story is "completely false" and that neither of them participate in such activity. 

Among Joe's former famous girlfriends are Taylor Swift, Demi Lovato and "Twilight" star Ashley Greene.