Which literary device is this?

I have heard many rappers today use this technique but I can't remember what it was called and it's driving me nuts! Kanye uses it saying "YOU'RE SUCH A ******* LOSER, YOU DIDN'T EVEN GO TO CL... BEUHLER" and "I AM NEVER SPRUNG, BUT I SPRING HER... JERRY". Jay-Z says "I CAN'T EVEN STOMACH MYSELF... ULCER", and Drake uses it "COME AND FIND ME... NEMO". Its quite a clever technique... they use the last word of the line and then they find something that sounds similar to it and rhymes. Its hard as hell to do while free-styling too.