It is bad to use other people's property without asking.
David has a tree with a branch that is growing too large and see his neighbor's chainsaw.
David wants to obtain the chainsaw.
David asks his neighbor if he can use the chainsaw.
David takes his neighbor's chainsaw without asking first.
David's neighbor will allow David to use the chainsaw and be open to lending David other items in the future.
David's neighbor will be annoyed with him and not let him borrow anything in the future.