Sometimes strapless strap-ons can slip out during frantic sexual activity. This is normal and will lessen as your pelvic floor becomes stronger. Try the following to prevent the strap-on from falling out: Change the sexual position to one that puts gravity in your favour. Missionary, spooning and cowgirl are all great. Try a bigger bulb. Use a little less lubricant. Strengthen your pelvic floor muscles using Kegel exercisers.