Strange weather,strange veges

Lately the weather has been extreme - in both directions. We will have a cold and very rainy day - the sort where I want to hibernate in the office - followed directly by a forty degrees celcius scorcher, which causes my cats to just flop out like expiring rag dolls.

Observe my deck, where you have to tread carefully to be sure not to step on a heat-exhausted feline. They don't bother to move, it's too hot for that, and humans are supposed to yield to cats, not the other way around. Obviously this is the way of the universe.
I don't know if it's an effect of the weather but I'm getting some huge mutant veges, some of which I'm not sure of. This giant below appears to be some sort of pumpkin/squash. Or, I've accidentally created a pumpkin/watermelon hybrid. It's got a lot of seeds in there and is definitely ripe, kind of hollow sounding, like a watermelon, but tastes squash-like.

If anyone knows what this is, please pipe up.
I'm also quite pleased that after last years caterpillar-fest, this year I have hardly any on the broccoli, in fact I've only found one. The broccoli looks great, which is awesome because it is one of my favourite sources of vegefied goodness. I've also got courgettes appearing randomly and they seem to grow practically as you watch - can go from small to overly large in one day. It's all quite exciting. I haven't quite got my green thumbs yet, but I'm sure they are at least green-'ish'.