Squeakers exist (and with the amount of parents buying these games for their kids how couldn't they?), but for some reason they seem to be far more common on console FPS. I've even heard quite a few that sounded not even like 10 years old. I'd make some quip about parents and letting their kids play such games, but I was allowed to play Wolfenstein 3D and Doom 1 with 6 or 7 years, so that would be kinda hypocritical.
PC has its fair share of them, too, but there they seem limited to "high profile" games like CounterStrike and Team Fortress.
Related anecdote:
I went to gamescom 2014 together with my brother who was wearing a shirt printed with his CS name and clan-tag and some friends of us (some also clan-tagged).
While we were sitting in one of the resting areas munching some burgers there was a small group of perhaps 13 or 14 year olds at the table next to us who kept staring at us and arguing to each other.
Listening in on their (quite loud, even against the background noise of the convention) argument it turned out they were recognizing my brother as "the guy who made one of them rage a few days ago" (pretty much a direct quote) and were discussing what the names of the other clan members of his in that game were and if they might be amongst the others in our group.
Pretty funny and we had a laugh about that for weeks.
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Captcha for this post: "Urban myth".
Haha Forum, very funny. Nobody likes a smartass.