Tub-thumping describes speech or writing that pushes an opinion loudly and forcefully — lots of shouting, lots of feeling, not much room for doubt. The image behind it is a street speaker banging on an upturned barrel to make people listen. It works as a describing word before a noun: 'a tub-thumping speech', 'his tub-thumping style', 'a tub-thumping patriot'. It also works as a naming word for the activity itself: 'there was a lot of tub-thumping at the meeting'. It is usually a criticism, but a softer one than most. Sometimes it is almost admiring, when someone means loud and stirring in a good way — 'a tub-thumping performance' of a song can be a compliment, meaning it had real energy. So the sentence around it matters. It is chiefly British, more written than spoken, and a little old-fashioned. Note it can be spelled tub-thumping or tubthumping.