When you are fingering multiple girls simultaneously, you may hear two orgasms of different pitches at one time (you must be going hard enough on both girls). These two sounds will make a slurring sound, hence the name sexslur.
Finger-banging your mom and your sister lsst night was pretty awesome! I went hard in at one time on both of them and I heard a great sexslur.
by imuyhg(notreall) January 15, 2012