Strange cups - what are they???

[Danmark]

I'll start off by saying that this may be the complete wrong place for these ( I am not even sure of the nationality ) so mods please do as you see fit.

OK, having said that, my father has had these two small cups / mugs for more than 50 years. He doesn't remember where they came from but he used to haunt military disposal sales in the 1950's. They are 2.5" in diameter by 2.75" high and have markings that "appear" to be dates and they have been made into mugs by soldering on a handle. As you can see there is the word 'TOP' on them and a 4/42 ( date? ) and a triangle below that with OPP within. Has anyone seen something like this? Would anyone know what they were originally? Are they even military?????

Thanks in advance, Dan

[brataccas]

they remind me of those trench art cups where the cup is made from a shell and a brass handle welded onto it