As in good, not as food but naming or calling something 'mustard' means this is good.

the act of texting people while you are pooping

Good, Pleasing to oneself, exciting

The vaginal smegma that smells like tear gas.

Another slang word for money, similar to 'cheese'.

A tangy sauce often put on hotdogs and hamburgers. Called mustard because it is in fact the same color as mustard

British slang, originating from Pilsley, Derbyshire: A weak expletive which shares both its definition and conventions of use with the word bastard. Originally, "mustard" was used to refer to a child born out of wedlock, but through a process of semantic broadening, it is now mostly used as a general pejorative term. It can be used both as a noun (see example one) and an adjectival intensifier (see example two). The word bastard is used in precisely the same way. As an antidote to your ignorance, other examples of intensifiers are: fucking, bloody, chuffing, sodding, etc.