Hold on to (someone or something) like grim death British verb phrase
To grip, grasp or hold someone or something tightly because you do not want to lose it or fall
As soon as the branch broke off, I held on to another branch like grim death.
When the robber tried to steal my backpack, I held on to it like grim death.
To hold something tightly, as though one's life depended on it.
The verb "hold" should be conjugated according to its tense.
A humorous way of saying that what one has said is just what they acknowledge and may not be entirely accurate
Mike: Have you returned from your vacation on the beach? Your skin seems to get tanned.
Jenny: My skin is always dark. That's my story and I'm sticking to it!