This means that somebody was too loud during sex the night before.\n\n'Microwave' refers to the coitus that was had.\n> Justine: Good morning, guys! How did you sleep?\n> Carla: Not very well.\n> Justine: why?\n> Carla: I heard you using the microwave last night..\n> Justine: Oh dear..\n> 'You're just jealous because you heard HER using the microwave but you can't handle that heat!'\n