 Liz Lemon ( Tina Fey ) comes home to find her wall full of knife holes , a great dane roaming her apartment , and a complete stranger on her bed , all courtesy of her boyfriend , Dennis Duffy ( Dean Winters ) . She breaks up with him , but Dennis claims squatter 's rights , so she gives him a week to move out . Liz and her friend , Jenna Maroney ( Jane Krakowski ) , go out to try to pick up some men , but are very unsuccessful . The next day , Dennis walks in to the staff office of TGS with Tracy Jordan , announcing he has found a new apartment and reads a heartfelt letter to Liz . The staff suddenly turns on Liz after Dennis walks out , and Jenna suggests to Liz that in light of the previous night 's disaster , she should re @-@ consider getting back together with him . She suggests making a list of pros and cons . Liz compiles her list of pros and cons . She marks down a positive remark after coming home to find that Dennis has cleaned up the apartment , put up shelves and a TV stand , and left her dinner . In the evening , Dennis returns with an early Christmas present for Liz . She invites him in , but soon sees Dennis on Dateline 's To Catch a Predator . As a result of this , Liz breaks up with Dennis , and marks it down as a con . 
