Give one student a warning about some small, insignificant action, e.g. 'If you drop your pen it'll break'. Invite learners to continue by taking the second half of your warning and creating a new warning, e.g. 'If your pen breaks you won't be able to do your exam'. Once this sentence is established, elicit the next warning - becoming bigger and stranger as they go on: e.g. 'If you can't do your exam you'll have to leave school' etc. At the end, see if learners working in pairs can recall the whole chain of warnings - starting from that one small initial action. Pairs should then create their own chain starting from a new warning.