The Tom-Tom joke is bizarre as it comes out of nowhere. It's like something from a third-rate sketch show. I often do not like the innuendo-laden jokes in new Who, but this is different. Not funny, but different and out of place. I share The Child's puzzlement.

EDIT: my own trip through the Matt Smith era has also gone slower than expected, as I find I don't like it as much now as I did on first viewing. Some of this may be due to my poor mental health, but I'm not sure how much, as I mostly enjoyed a diversion into The Sea Devils. Re-viewing Deep Space 9 often seems more tempting, though I feel like a traitor for saying so (I got the complete box set for Chanukah and have just started season two).