Xiàbān yǐhòu, tā cháng zhǎo lǎo péngyou dào dao kǔshuǐ.
After work he often finds an old friend to vent to.
Tips
memory
Literally 'pour out the bitter water': 倒 (dào, pour) + 苦水 (kǔshuǐ, bitter water — the buildup of complaints). Like English 'to unload', it implies the listener is doing the speaker a favor by absorbing the negativity.
grammar
Verb-object compound, so 倒 and 苦水 can be split: 倒了一肚子苦水 (dào le yī dùzi kǔshuǐ, 'poured out a belly-full of grievances'), 倒倒苦水 (reduplicate to soften, 'have a bit of a vent').