Dungeons and Dumbasses, or Why We Can't Run Nice Games

Over the past few days, a few comrades in a scout troop and I had the good fortune of being DM'd in our first D&D campaign by one of the older scouts. It was an altogether pleasant run, although it devolved into a circlejerk of running gags.
The first of these was everyone's character speaking Ebonics as a tertiary language.
Second was my wizard always casting spells in the shape of a dick. This arose out of a fucking bugbear Tarzan'ing into my squishy Eladrin wizard from a chandelier, one-hit bloodying me. On my turn, I run away and shoot a magic missile. DM asks me to describe it. "A dick. A big fucking dick comes out of my wand."
Third was goats. The DM was describing a giant spider, and he accidentally said "Goats for teeth" when he meant "teeth the size of goats." Suddenly, every unseen enemy was a goat. The house (a necromancer's living house) was just one big goat.

Does it get better if I run a game with kids who aren't seventh graders?

Ouch.

Nope.

Last year, playing with grade twelves and elevens, in our first game together a player attempted to placate a CLEARLY panicking woman by hugging her. We tried to convince him otherwise, the DM asked him if he was sure, he wouldn't dettered, so the DM responded "fine. Roll for sexual assault".

Turns out she was a 5~ level mage, and she immediately dropped me and the fighter in question to almost no HP.
at the start of an encounter.

All I can say is thank god I had enlarge person prepared.

Yes, it does get better. You need to, with the party and GM, agree as to how silly you'll all let things get. A little is fine, but it sounds like yours hit the point where it eclipsed the rest of the experience.

This was more of a one-shot campaign. The DM says he has a campaign running where I'd be welcome if I was able to come.

It's a matter of having a good GM and mature players who legitimately want to put together a good game. But yeah, I'll just echo Ji here.

Of course, my grandma has to go all "devil's game" and blame it for my dad being a worthless piece of shit.

Look, tell your grandma this. If it's Satan's game, I'm still waiting for my magic powers, damn it.