"I'm not exactly known for my jokes" is a kind of understatement for comic effect. It literally means "I'm not famous as someone who tells jokes well." But the speaker really means "I'm terrible at telling jokes." Similarly, I sing but I don't sing well, so I might say "I'm not exactly Frank Sinatra." I'm assuming "shooer" is not a misprint for "shooter." "Shooer" isn't a word, but its meaning is clear. It means "a person who shoos." "To shoo" means "to drive unwanted animals away." If a stray cat came into your yard, you might yell "Shoo!" at it. So this is someone who's been given the job of "shooing" something away. Given the joking nature of the talk, it might be people, not animals, who are to be "shooed." In informal English, it is fairly acceptable to manufacture words on the spot by combining them or adding well-known prefixes and suffixes. However, it would be better to write the word as "shoo-er" rather than "shooer."

What you're "known for" is what you're famous for. In other words, the first (or one of the first) things that people think of when they hear a person or place. So, France is "known for" its wines (among other things). Santa Claus is "known for" giving gifts. The person here is saying "I'm not famous for my jokes". Meaning "I don't joke much, if at all." I've never heard of a "shooer". Maybe it means a bouncer like at a nightclub. If you could provide the original source of this extract then that might help figure it out. :D

'I'm not exactly known for my jokes' means that he doesn't usually tell jokes