Dude 1: “You just took a dump in the bathroom and didn’t wash your hands? That’s disgusting AF!”
Dude 2: “No man, I washed my hands”
Dude 1: “Lies bro! I took a piss right after you bombed the bathroom and the sink was bone-dry! You are dry sinker!”
A phrase stated after something/someone has been easily fooled or lured in. It has its roots in fishing lingo, referring to a fish having fallen for the bait easily; swallowing the hook, the fishing line, and the sinker along with it.
I jus' put out a sign this mornin' readin', 'BABY HOGGS 4 SALE CHEEP. CAWT WILD YESTIDDY'. Boy, I ain't neva' seen so many folks come runnin' to the ranch! Leetle did they know I breed them hawgs muhself. Tee hee! Hook, line and sinker! Haw haw!