All the other replies tiptoeing around this - OP, your son has hormones raging in his body, he's going to masturbate a lot. In my opinion and I'm going to be blunt, maybe focus on:
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letting him know it's normal for all this hormonal activity, masturbation is OK and not something to be frowned upon or ridiculed (well unless you two joke a lot which would be cool). In fact, as he starts to go out on dates gently suggest he rub one out before the date to calm his hormones the F down, which leads me to...
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he's gonna get boners all the time, it's just a thing that comes with all those raging hormones. It can happen in unfortunate places and unfortunate circumstances (8th grade science class wearing stretchy shorts? SURE WHY NOT), so as a mom be aware this could be happening but he of course doesn't want to say anything to you. Ignore or treat it as normal (or again, bust a joke if you're tight like that).
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teach him to respect his partners and not be just letting his hormones take over and he wants to stick his dick in everything. This is I feel something is missed on all "sex ed", to me the biggest part is not the physical act but the negative emotional results if he lets those hormones take over. Hetero or gay doesn't matter, it's all the same - your partner has feelings and be aware ("don't be an f'ing asshole").
I'm of an age these days, but man I wish someone in an adult capacity had covered the above when I was a teenager. Instead, growing up with repressed catholic type parents it took me way, way too long to grasp the above on my own.
I fear you may have misread my intention in comment; nothing nefarious intended, it's about the "no updates to this app for years" which can equal "security issues unpatched" for the average, regular person. You did not disclaim the above details in your OP, you are NOT a normal user and had I known that I would never have commented.