After another incident, his mother rants to his father that Calvin wasn't all her decision. His father responds that he offered to buy a dachshund.
In one strip, Calvin's mom is watching TV and Calvin is complaining about all the kissing the characters are doing. His mom announces "bed time!" and carries him up to his room. The last panel has a bewildered Calvin remarking, "There's a connection here, I just know it."
One strip had Calvin ask his mother why it was "worth $5 a minute to talk on the phone to goofy ladies who wear their underwear on TV commercials," which leads, quite explicably, to him getting all of his television privileges revoked.
A number of early strips see Calvin trying to get into or rent R-rated movies with pretty suggestive titles, like "Venusian Vampire Vixens", "Attack of the Co-Ed Cannibals", or "Cannibal Stewardess Vixens Unchained."
In one strip, Calvin's gum-chewing leads to the memorable line, "An orifice is an amusing thing, alright."
At the end of one strip, Calvin's dad receives a call from his wife at work to which he answers: "Look honey, could we talk about that operation some other time?" What's the context? Well, Calvin had just been asking his mom for a baby brother, but only so he could have someone smaller to bully.
This Strip (the one with the anatomically correct snowman) isn't so much getting crap past the radar as dropping its pants in the front yard and screaming "HOW DO YA LIKE ME NOW?!"
After a week-long camping trip suffused by rain from beginning to end, only for the sun to appear immediately after everything was packed up, the final panel combined a Noodle Incident and an implied Cluster F-Bomb. Of course, given the father's reaction when he drops something heavy on his foot, it may simply have been a cluster Angrish bomb.
Calvin(eagerly): Did you know what any of Dad's words meant?
Hobbes: No... but I wrote 'em down. We can look them up later!
There's a strip where Hobbes mentions that he reads National Geographic for the hot tigress babes on the cover. Wellplayed, Mr. Watterson.
For one show and tell, Calvin told his class that his mother dons "a patriotic leotard, a cape, and knee-high, high-heeled boots" and fights crime as a superheroine. In the last panel, as the mom is handing the dad the note from the teacher he remarks, "Wow, show me that outfit sometime."