Nothing like this happens in the Lego movie - explaining the facts of life, with help from the pigs

When answering awkward questions for our two children, it has proven useful, being keepers of pigs. 

A few days ago, Smudge (aged 8) asked the big question in the car - how are babies made? Both his dad and his older sister told him Mummy could answer that. Mummy wasn't there, so Smudge had to carry on to school in ignorance that day. 

He asked again at bedtime when Mummy, a reliable source of accurate and well-explained information on many topics, was available. ​

Offsetting the answer into the world of pigs is a really useful mechanism, in that it softens the nature of what you're about to say, which can be alarming to an 8 year old. After all, nothing like his stuff happens in the Lego movie. 

'Well, you know when Daddy wants Rosie to have piglets, he puts her in with Kevin, doesn't he?' I began. 
'For the mating?' asked Sam. 'What happens in the mating?' As a farm-kid he's already au-fait with some of the terms even if he doesn't fully understand the technicalities. 

So I explained what Kevin the Berkshire boar puts where, and how some seed shoots out at high velocity and finds an egg inside Rosie the Saddleback sow, and then together the seed and the egg grow into piglets. Or a baby. Smudge was smiling shyly and evidently following, but clearly still needed clarification. 

'So is it the same in humans?' he asked. 
'Yes,' I replied in my best pragmatic manner, whereupon I could see him making some quick calculations in his head. 
'So you've had to do that twice?' he said. 

I know that you're not supposed to laugh when having a discussion of a sensitive nature with your child, but I'm afraid that's the point at which I lost it.