If you are stiff in a dream, then it could show the stress and intensity you are suffering from. Probably you feel you are victimized at some point, therefore you are afraid to make a move and instead of that you are staying stiff.
Dream dictionary: Stiff dream meanings
…To dream of polite people is a sign that a stranger will visit, or be introduced to you: if a girl dreams that her beau is stiff and formal in addressing her, it foretells that she will soon have a new admirer. Lucky lottery dream numbers – 61….
…Dreaming that your knees are too large, denotes sudden ill luck for you. If they are stiff and pain you, swift and fearful calamity awaits you. For a woman Dreaming that she has well-formed and smooth knees, predicts she will have many admirers, but none to woo her in wedlock. If they are soiled, sickness from dissipation is portended. If they are unshapely, unhappy changes in her fortune will displace ardent hopes. Dreaming of knees is an unfortunate omen….