Often expressed on the internet with a long line of random letters typed quickly, furiously and usually impulsively. There's no specific word for it.
Can also be used to express shock and utter excitement. Spelling typos often ensue. In real life these chains of letters are usually used while having a seizure.
Possible spellings of "frustration":
Adfasdaflksdfl;askl;apdsfkfkewo my computer broke
OMGOMGOMGSDFSADFSDF TWIIGLLIGHHTTT COMES OUT NEXT MONTN DFDSAFdsfasdfdcsdcsdcfSDFSDfsdfsfsdfsd