Steve C said:
His pocket was evidently larger than you assumed.
Then again, maybe not...
Zeiss does make a couple of monoculars that are about the size of a pen. I think they are called Design Select and come in 8x20 and 10x25 configurations. They also make a couple with lower magnifications. Nikon makes a 5x15 monocular that is a bit larger than the Zeiss.
A monocular might be smaller, lighter, and less obtrusive in the pocket (though not necessarily so) but, I'm not sure they would provide very good views, especially for any kind of extended viewing. I have a laser range finder that I use quite a bit and its monocular is just not very nice for general viewing. It works for what it was designtd to do but, it definately never replaces a good binocular. Good monoculars are also almost as expensive as decent compact binoculars.
The absolute best pocket binocular I have ever handled (as far as compactness and low weight) is the 8x20 Zeiss ClassiC (now called the Conquest). It's optics are pretty darn good too. This little binocular will dissappear into the pocket of a dress shirt with no problem. It usually retails for I think, around $300. My little Pentax DCF MC II is indeed bigger than this Zeiss but, it still is quite acceptable slipped into a trouser pocket. It is definately significantly smaller than the DCF MP you currently have. This is helped by its double-hinge design which allows it to fold into a much smaller size than is possible with the larger Pentax.
Of course, some of the answer to your question is going to be dependant on just how comfortable you are carrying things in your pockets. My younger brother, for example, cannot stand to have anything but his wallet, a small key ring, and his very small cell phone in his pockets. I, on the other hand, between pants, shirts, and jackets carry a whole bunch of stuff with me all the time. So much so that most people gape in disbelief when I empty all my pockets.
If you tend to lean more toward my brother's way of thinking, you are going to find it difficult to find anything that won't bother you. If you are more like me in this respect, there are some pretty darn good options available to you.