make the (bed) springs creak

   to copulate

   The usual bed² imagery. The springs may also squeak under the same provocation:

    We've been married a long time and made the springs creak times without number. (Fraser, 1971)

    'It would improve everyone present if the bedsprings squeaked a bit more often.' 'Let's leave sex until after tea,' said Treece. (Bradbury, 1976)