When someone does something in a slipshod manner, they do it in a way that's careless and sloppy — that isn't right.
An easy way to remember the meaning of slipshod is to note that "shod" is part of "shoddy," another word for slipshod. (Alert: despite their similarity, slipshod isn't genetically related to shoddy.) Or you can use "slip" to clue yourself in. Originally, someone who looked slipshod was wearing worn-out slippers: they were shod in slippers.