I got a kick out of this Mutts strip from September.
Mutts for 2018-09-13 © 2018 Patrick McDonnell.
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 any 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.
[*While I’m not sure the other “walls” have a conventionally accepted numbering, if
you count from the left clockwise in a plane intersecting the flat page or screen (or the proscenium of the stage, from whence the concept originates) — the second/middle wall being the background, parallel to the unseen “fourth wall” through which we view the action — you end up with the left and right walls being the first and third, respectively.]