There is NO truth to that at all.
Hi,
Someone has played mischief on you, there is no evidence to prove that sore throat can be reduced by sucking the genitals. There are many causes for sore throat, like long standing sinus problems, gastric reflux, recurrent infection of the pharynx and tonsils.
Get yourself evaluated from an apt ENT specialist and also try taking medicines depending upon the cause. Drink plenty of warm water, avoid smoking and eating greasy food. Any more doubts you are welcome.
Regards
OHNS2010