(Strip Number 149, Original Publication Date, 15 July 1981)
Panel 1: We find ourselves on the two-lane country roads that John traveled down to get to Not-Ted's-cabin to avoid gridlock waiting for Mike to relieve himself. As John's elbow juts out the driver-side window and as Farley sniffs a bush, Elly, who's holding a role of bathroom tissue, narrows her eyes in frustration to Michael's off-camera yell "Because I don't want anyone to see me, that's why!!" which, as could be expected, is in response to her asking why he went so far into the woods.
Summary: It would seem that Elly is pissed because Mike isn't being a real, basic human being and taking a dump in front of the family; that being said, it's clear, at least to me, that she would resist doing likewise. In her mind, it's worth the five minutes of daylight she'd have burned because, as an adult, she privacy.