Oh I don't know the IRA were fairly partial to them - I go my eardrums rattled by one back in the 1970s. Oh course the earlier poster was correct. Most bombs with a time delay do not have pretty flashing lights or digit counters telling you exactly when they are going to blow, they just go bang when the time comes.

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Note 1. All requests for planetary demolition must now be submitted in quadruplicate on form UX-565/B4 and be counter-signed by the assistant administrative officer for interstellar traffic calming - department QG-7. Subject to approval by the chief planning officer and the infrastructure development coordination sub-committee.