Your second cousin's son (or daughter) is your second cousin, once removed.
The sons of your father's sister are your first cousins.
Your uncle's sons and daughters are your first cousins.
Your mom and her uncle's son are cousins, of the same generation, first cousins. Your mom's uncle's son is your first cousin, once removed (by one generation). If he has children, they will be your second cousins. (Children of first cousins are second cousins to each other.)
Your first cousin is your son's first cousin once removed.
Your uncle's wife is your aunt and her children are presumably his children, too. They are your first cousins. If your uncle's wife has children from a previous marriage, you are not related to them because you have no ancestors in common. However, if your uncle married her while the children were very young, they may effectively be treated as your first cousins.
Your son and your nephew are first cousins to each other. Their daughters are second cousins to each other.
Most students never call their first cousins and some don't event know who they are.
Dads typically call their sons by their first names or nicknames.
Your baby and your cousins are first cousins once removed to each other. You baby and your second cousins are second cousins once removed to each other.
Your mother's sister's children, sons or daughters, are your first cousins. The children of first cousins are second cousins to each other. That is the relationship between your children, or either sex, and your first cousin's children, of either sex..
You and your father's first cousin are first cousins, once removed.
The children of your first cousin are your first cousins, once removed.