"You suck" has lost more and more of its vulgarity over time. While it is definitely rude, it has gained less offensive meanings when used among friends. Examples: Person A: "Hey! I won the lottery!" Person B: "Wow. You suck! I've been trying for years!" Translation: "Wow. That's so unfair! I've been trying for years!" or Person A: "I can't beat this level! It's so hard!" Person B: "It's not actually that hard. You really suck at this game." Translation: "It's not actually that hard. You really are not good at this game" There are a variety of uses for this word, but it is important to know that it can be very offensive if used with the wrong people. It's best to not use this word at all if you think you might offend somebody, but it is also important to keep in mind if somebody uses it with you they may not be aiming to offend you if you are close friends. It may just be friendly banter. With this said "This company sucks" would be the grammatically correct phrase to use. "this company is shit!" is far more vulgar than "this company sucks", but I would avoid using both phrases if you are trying to sound polite. Hope this helps :)

"you suck" means "you are awful/rubbish/terrible (at something)" or just "you are lame". "suck it" is similar to saying "f*** you" but not as rude. You can say "this company sucks" or "this company is shit" Regarding the sexual meaning, "you suck" would be a comment and "suck it" (or "you, suck") would be a command.

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