Tie your ankles to your thigs as in a
frogtie (it's up to you if do it completely naked or wearing pantyhose as in the pic), then go on all four (of course, being so tied it will be on your knees, use a couple of pads or pillows under them) and masturbate while humping something vertical (a table's leg, the corner of your bed, anything suitable). Of course you can go on knees and face, to let your cunt be more in contact with the object you're humping and/or have your hands free for clit/tits stimulation.