There was a game that already did this.. not sure about the name and if I find it I will edit the post, but you basically spammed the language in chat and the skill in that language went up and as you gained skill you began to learn it. There was people that would macro 4 or 5 lines of the language and spam it, would charge you x number of gold to learn the language they were teaching.
EDIT: Found it, the original Everquest, was a game that if you didn't know a language someone was talking you would get;
Tredo says in an unknown language: GEBg9oagua wiounag argiaf agiuabng
I could spam tells to you or in open chat I could just keep talking in that "unknown language" and you would begin to learn it.
Your skill in dwarf has increased to 4
spam
spam
spam
Your skill in dwarf has increased to 5
spam
spam
spam
Tredo says to you in Dwarven: Is it starting aaubnaserg aguibae adfgbiugr if not agauinae then arguinar
spam
spam
and so on... till you could read what I was saying and your skill was 20 or whatever the max was... I don't remember.
2nd edit: Here is a post I found on the Everquest forums. It depicts how the game starts with the languages already on a character.
Here is a list of all the languages available in that game;I wanted to determine the language that each race starts with, so I created new characters of each race and noted the languages that each had. All races start with 100 in Common, with the exception of Ogres, Trolls, and Iksar which start a few points shy of 100. All races start with 100 in their racial language. I've left that data out of the below list, except in the case of the Half-Elf and Iksar where there is a tad bit of ambiguity about the racial language. If a race isn't listed, then it doesn't know additional languages beyond Common and it's racial language. Let me know if you notice any errors. Thanks!
Dark Elf: Elvish (54), Elder Elvish (54), Dark Speech (100)
Drakkin: Dragon (100), Elder Dragon (100)
Dwarves: Gnomish (25)
Frogloks: Troll (42)
Gnomes: Dwarvish (54)
Half-Elves: Elvish (100)
High Elves: Dark Elvish (51), Elder Elvish (51)
Iksar: Lizardman (100), Dark Speech (100)
Ogres: Dark Speech (100)
Trolls: Dark Speech (100)
Vah Shir: Erudian (32), Combine (100)
Rogues start with 100 skill in Thieves Cant.
Common Tongue
Barbarian
Erudian
Elvish
Dark Elvish
Dwarvish
Troll
Ogre
Gnomish
Halfling
Thieves Cant
Old Erudian
Elder Elvish
Froglok
Goblin
Gnoll
Combine Tongue
Elder Teir'Dal
Lizardman
Orcish
Faerie
Dragon
Elder Dragon
Dark Speech
Vah Shir
I could see where this could be fun... it was fun before in EQ.