my son; one's son
Humble (kenjougo) term used to refer to one's own son when speaking to someone outside the family. Not used for someone else's son.
Slang usage, likely derived from the homophony with 愚息 (humble 'my son'). Rare and vulgar; not used in polite contexts.
See also: 息子
My son is in your care.
My son graduated from university this year.
On internet forums, 愚息 is sometimes used as slang for the male genitalia.