Clean Cartoonists' Dirty Drawings

Amazon says:
The classic American comic strip is known for being wholesome family entertainment, accessible to everyone. But these artists, including Sidd (B.C.) Hoff and Mort (Beetle Bailey) Walker, also had a mischievous side they only shared with peers and friends. Now, in Clean Cartoonists' Dirty Drawings, the general public can see the work of these American masters in their moments of blue humor.

Clean Cartoonists' Dirty Drawings

Via.