A student (male, from the handwriting) once suggested to the administration that "Professor Rubin should be executed on public television". Left to the reader as an exercise: did he mean broadcast television generally (as opposed to cable), or the Public Broadcasting Service specifically? I'm not sure ratings on the latter would justify my sacrifice.
This evaluation came in a freshman-level mathematics course I taught as a graduate assistant. As I recall, the course was populated mainly by juniors and seniors who had deferred it as long as they possibly could, and now had to face the music. The department evaluation form had a number of criteria on the front, with scores on a scale from 1 (excellent course/instructor) to 5 (terrible course/instructor). On the back there was space for an essay. The student (again, male based on handwriting) circled 5 for every question on the front, then wrote on the back "Best prof I've had at MSU!" Neglecting the minor discrepancy of calling a TA a "prof", this again introduces an element of uncertainty: did the student mistake the direction of the scale on the first page, or was he testifying to three or four truly horrid years of college?
And The Winner Is ...
My single most memorable evaluation has to be seen to be appreciated. It was submitted in a junior-level lecture course on quantitative models, required of all business undergraduates and populated primarily by seniors who had run out of room to procrastinate. Handwriting suggests a female author. The evaluation is actually quite lucid and rather well written. You can see by the author's use of available space that her response was rather impassioned (and prone to setting off Geiger counters).
One line from the first page clinches the trophy for this submission. The question asks for input on "Reading materials and written and oral assignments". The first line of the young lady's response: "Overhead packets [copies of transparencies used in lecture] were good but often times confusing as the formulas contained so many consonants."
I received this evaluation at the end of a fall quarter, and I was scheduled to teach the same course twice more that academic year. In the first class of winter quarter, amid the usual "welcome to the course" stuff, I mentioned that when I wrote a formula on the projector, students should treat 'Y' as a vowel. Unsurprisingly, most of them looked a bit confused at this.
There is one more anecdote to pass along about this. Years after collecting all three of these submissions, I was attending a social hour for MBA students and chanced to speak with a brand new student from Korea (the one with the functional economy). He suggested something -- I forget what -- that arguably would have enhanced learning in the core quantitative methods course (which I taught), but at some cost to students' peace of mind. I explained to him that if I tried to implement his suggestion, students would "rip me a new one" on the evaluation forms. He asked me what I meant by "evaluation forms", and I explained our system to him. At the end of my explanation, he looked me square in the eye and said that the system was "stupid".
I learned that, approximately a year later, his undergraduate institution in Korea implemented evaluation forms.