'pozor' in Czech means 'watch out!', but means 'shame' in Russian
droga in czech means drug, in polish it means road
záchod in czech means toilet, zachód in polish means 'west'
odchod 'to depart' in Czech means very specifically 'to depart by foot', while in Slovak it has a bit wider meaning, and buses and trains also combine with 'odchod'. To a Czech speaker this gives the funny implication that departing trains grow legs and walk out of the train station
Croatian 'mrdati' = to wiggle, means 'to have sex' in Czech
'Čerstvý, voňavý chléb' is Czech for 'fresh, nicely smelling bread'. In means the opposite in some slavic languages 'stale, stinky bread'. This kind of 'good meaning in one but bad meaning in other' duality happens surprisingly often actually, see also úžas and odporný above
otrok in Czech means 'slave' but in Slovenian and perhaps other South slavic languages it means 'child'. Very funny when combined with bazaar, turns a perfectly fine baby bazar into a slave bazaar
My friend has a fun sentence from Slovenian - "Hitri otroci kuhali jed na Dunaji". Literally none of the words here mean what a Czech thinks they mean. No not even Dunaj. Czechs read it as 'smart slaves were disemboweling poison by the Donau river', original Slovenian meaning is 'fast children were cooking food in Vienna'
Edit: wait one more. "srpanj" in Croatian means July, "srpen" in Czech means August. Listopad in Croatian means 'October', in Czech means 'November'. rujan in Croatian means 'September', říjen in Czech means 'October'. kwiecień in Polish means 'April', kviteń in Ukrainian also means 'April', květen in Czech means 'May'. Months are fucked up.