“Why was the student’s report card wet?”/“Because his grades were below C-level.”

A report card riddle is:
 
Q: Why was the student’s report card wet?
A: Because his grades were below C level.
 
The “C level” (sea level) joke was printed in several newspapers in 1973.
   
     
30 April 1973, Miami (FL) News, “Mini Jokes,” The Mini Page, pg. 3, col. 1:
Q. Why was the boy’s report card wet?
A. Because all his grades were below C level.
—Robbie Dekle, age 9, Palm Springs
 
8 July 1974, Pittsburgh (PA) Press, “Mini Jokes,” The Mini Page, pg. 3, col. 1:
Father: Why is your report card wet?
Son: It’s below sea level.
Judi Sherbondy (Greenville, Pa.)
           
29 October 2003, Los Angeles (CA) Times, :The Kids’ Reading Room; Jokes & Riddles,” pg. E17, col. 3:
Why was the student’s report card wet?
Because his grades were below C level.
Aniqa, 9
Grant Elementary, Los Angeles
 
Google Groups: alt.humor.puns
Puns of the Weak 10-31-03 Part 2 The Rest of the Puns
Stan Kegel
11/1/03
(...)
Why was the student’s report card wet?
Because his grades were below C level (Aniqa, 9)
 
Twitter   
eh.
@Shark_Bait10
Why was the students report card wet?
Because his grades we’re below c-level
12:59 PM - 24 Oct 2013
   
Twitter
Lexi Stewart
@red_pedestrian
“Why was the student’s report card wet?” “Because his grades were below C-level.” #laffytaffyjokes
10:51 AM - 31 Oct 2013
   
Google Books
What a Joke!:
For Kids of All Ages
By Marlize Schmidt
Lulu Press (Lulu.com)
2014
Pg. ?:
Q: Why was the student’s report card wet?
A: It was below C level.
 
Twitter
Finn Rose
@muFinnmanRose
Why was the students report card wet?
Because his grades were below C-level.
Hahaha. Pls someone get me food, stuck eating laffy taffy.
1:12 PM - 3 May 2014
     
Reddit—Teenagers
Why was the students report card wet? (self.teenagers)
submitted February 7, 2018 by HarvMan5317
It was well below C Level
 
Reddit—Jokes
Why was the students report card wet?
submitted April 19, 2018 by _Jordee123_
It was below C level!
 
Reddit—Cleanjokes
Why was the student’s report card wet? (self.cleanjokes)
submitted June 28, 2018 by madazzahatter
It was below C level!