A Question about the Post Office

I was in the Post Office, posting a parcel so I walked up to the desk.

'Can I send this second class, please,' I ask, putting the parcel on the scales.

The woman looked up at me. 'And can I ask what in the parcel for security reasons?'

'It's a book,' I answer, cursing myself that I didn't plump for one of the 'funny' replies I always have ready. It's not just the obvious 'yes, you can ask me what's in the parcel' or even the pedantic 'there's nothing in it for security reasons'. I mean the answers I have like 'some frilly underwear that was chafing me when I bend over' or 'the Big Book of British Soup'.  There are a few more vulgar that always tempt me. I sometimes wonder what they'd say if I replied 'a partially masticated butt plug' or 'a pair of prosthetic buttocks'. If I could sit down (on my prosthetic buttocks), I'm sure I could come up with some pretty imaginative answers but I haven't and so I didn't. Instead I just added a bland:

'I keep thinking I should give you a silly reply.'

'Oh,' said the woman. 'We get loads of them.'

'Really?' I ask, a little surprised.

'Most people say it's a bomb.'

I did a double take.

'Did you say bomb?'

'Yes,' she smiled. 'Most people just say they're sending a bomb.'

'Don't they get into trouble?'

'Oh no,' she laughed as she affixed the label. 'Good job we don't take them seriously!'

Which made me think. The Post Office are always asking us what's in the parcels for security reasons, to make sure that it's not a bomb. Yet when you tell them it's a bomb, they don't take it seriously. Which begs the question: what kind of reply would make them really suspicious?

[Addendum. It suddenly struck me that perhaps bombs aren't actually on the list of objects you're prohibited from sending through the post. They keep showing me the list and I'm not sure that I've ever seen a bomb of that sheet. Perhaps it should. I'd even suggest that it should be at the top of the form.]