Okay, so there's a comedy duo in Japan called Sandwichman, and many of their skits start with one of them standing outside a place, talking to himself:

こんなところに〇〇があるな。ちょっと入ってみよ。ｳｨｰﾝ
(Oh, there's a [store/place] here. Guess I'll take a look inside. *automated door sound*)

Kanon's line in this image is a parody of that opening line, with a pun on Wien's name and the ween sound of an automatic door opening.
Incidentally, the member of Sandwichman who usually says this line is Date Mikio, the uncle of Date Sayuri (Kanon's voice actress.)