Since you ask here are some photos:
And a special thanks to zoltar7. Great info! 
Does it have any markings on the bottom?
OK, now that that one has been translated, how about this one?
It says “In mirist Wahrheit Jeh kann nicht trugen” And the other side says “Gift trinktman nicht aus solchen Krugen.”
Thanks.
It has these stamps on the bottom and this (datecode?) that is hidden in the forest behind the handle. I’m fairly certain that the date is correct because I asked the original owner at the auction when she got it and she said it was acquired on her college trip to Germany in the mid 60’s.
It should be ‘In mir ist Wahrheit’. I’m having trouble parsing the rest. Is ‘Jeh’ short for ‘Jedermann’ (anyone)? It seems to say something along the lines of ‘In me there is Truth: Anyone who drinks from a (Krugen) such as this can’t carry poison.’
Am I at least close? 
Edit: spelling
Zambini, not German myself, but my university German suggests,
“In me there is a truth none can mislead;
One drinks no poison from such ‘Krugels’” (a big size of beer mug-- these days 1/2 liter)
nitpick: Krug on its own is the singular form, Krugen is simply the plural (required here).
Proper word separation:
In mir ist Wahrheit
Jeh kann nicht trugen
Gift trinkt man nicht
aus solchen Krugen
If trugen has an umlaut (trügen) than it’s ‘deceive’ (as in capybara’s reading).
If it actually has no umlaut trugen, it’s an archaic or possibly dialect form,
and would mean ‘bear, carry’ (i.e. “not everyone can bear”)
Trying to see if this phrase had a source led to this :
1001 German Beer Stein translations
Which includes “In mir ist Wahrheit/ich kann nicht lügen” (In me is truth, I cannot lie).
Missed the edit window, but forgot to mention :
Krugen would have to be an archaic or dialect plural. Krug might also be irregular and add an -n in this case (the dative); normal German plural is Krüge so it might be Krügen.
Krügen is a dative plural, the appropriate case for prepositional phrase indicating a source. I’d say it’s completely regular. The funny thing is that second language speakers of German use elaborate classification schemes for declensions and conjugations but native speakers don’t do that. We just know all the plurals by heart and the rest follows naturally.
Could the e in Jeh be a c? If the “J” doesn’t descend below the baseline, then it’s actually a slightly old-fashioned I. (Btw. that’s also the reason why the German rifle caliber 8x57 IS is sometimes called 8x57 JS in foreign languages.) Ich would make perfect sense in that place and the whole line would be: I cannot deceive.