What the hell does this mean??

What does the saying " Dont suck if it isnt sucking" mean?? I heard tico say it once then i heard it again on tv last night. The only thing i can think it might mean is dont moan if soemthing isnt that bad?? Its a weird saing anyone know wot it means?

I think it might mean something like don't mend it if it's not broken. Of course, you know English is nmot my mother tongue, son I'm guessing here! :P

its yankee so really not worth knowing :P