I got a kick out of this Mutts strip from September.
The most amusing part to me is that it doesn’t really break the fourth wall but accomplishes something very like what we think of as breaking the fourth wall by not breaking the panel’s third* wall, surprising the characters — and in turn the reader — by suddenly reneging on the contract that allows panel borders to be drawn in the same ink as lines defining solid objects within a strip’s panels yet be traversable by said objects as portals to the rest of the world being depicted.
