get on (one's) hobby-horse

To frequently or incessantly talk or complain about a subject, topic, or issue in which one is excessively interested. Ah, here we go again. Once grandpa gets on his hobby-horse about the government, there's no stopping him!

Common Names:

Name	Pronounced	Usage
Tatjana	TAHT-yah-nah (Finnish)	Serbian, Croatian, Slovene, Macedonian, German, Latvian, Lithuanian, Finnish
Amalthea	-	Greek Mythology (Latinized)
Kunegunda	kuw-ne-GUWN-dah	Polish
Rohesia	-	Medieval English (Latinized)
Faraji	-	Eastern African, Swahili
Lew	LEF	Polish