Bad grammar is bad

You're / Your
Your is possessive, in other words you own something: Your dog crapped on my lawn.
You're is a contraction of you are: You're definitely cleaning that crap up.

Lose / Loose
Lose is the opposite of win, The wallabies will lose to the All Blacks in the Bledisloe cup.
Loose is not tight, the wallabies have loose discipline.

Weird / Wierd
Weird is correct, E before I.

Their / There / They're
Their is possessive, meaning it owns something: Your dogs are responsible for their crap.
There refers to a place or idea: Your dog crapped there. There are good reasons for your dog to crap elsewhere.
They're is a contraction for they are: They're crapping on my lawn.

It's / Its
It's is a contraction for it is or it has: It's crapping again. It's crapped again.
Its is indicative of possesion: You had better clean up its crap.

Effect / Affect
Effect is a noun: There was no effect when I kicked your dog.
Affect is a verb: The dog is affected by the crap you feed it.

Then / Than
Then is used for time: First he sniffed the grass then he crapped on it.
Than is used for comparison: That's a bigger pile of crap than the last time.

Definitely / Definately / Defanataly / Defanitely / Definetaly
There is no A in definitely.

A lot / Alot
Alot is not a word: Your dog craps a lot.