Men are walking around like ticking time bombs, completely oblivious to the danger they face.
Times, Sunday Times (2014)
There's no ticking biological time bomb, no urgency.
Times, Sunday Times (2010)
But he had no idea his heart was a ticking time bomb until four days after he suffered chest pains when he went to hospital.
The Sun (2011)
Definition of 'time bomb'
time bomb
Explore 'time bomb' in the dictionary
countable noun [oft adjective NOUN]
If you describe something as a time bomb, you mean that it is likely to have a serious effect on a person or situation at a later date, especially if you think it will cause a lot of damage.
Definition of 'tick'
tick
(tɪk)Explore 'tick' in the dictionary
verb
When a clock or watch ticks, it makes a regular series of short sounds as it works.