They are in the showers. One side has a slot and you pull it out (like a tape measure). You pull it out and hook it into the slot to make the clothesline.
ASMo Buzz Lightyear building definitely has them. Ours was up, and the spring was broken in the retractable portion, so we had to leave it up, even though we didn't use it.
It is in the shower just below the shower curtain rod