Mark Tartulli's comic strip Lio often ventures outside the confines of the genre -- especially when it comes to the convention of comic strip panels (see Lio and the Fourth Wall) for other examples). In his 4/9/14 strip, Tratulli has Lio once again break the fourth wall -- this time painfully.
Tartulli's not just an imaginative cartoonist, but a gifted one, too. Consider: if you were going to draw this gag, where would you place the elements? Knowing that the eye reads left to right, Tartulli arranged them to maximize the humor.
First we see Lio -- what happened? Then we see the cannon (with the note "for outdoor use only") and then Lio's pet squid with the instruction sheet. Each element reveals another layer of what just happened, and adds to the humor.