Hilary Price’s Rhymes With Orange plays with phrasal portmanteaus based on overlaps:
Fond memory foam bed is based on two two-word expressions, the A + N combination (a common collocation or cliché — depending on your opinion of the combination) fond memory and the N + N compound (a kind of commercial jargon) memory foam bed. (I call this a portmanteau rather than a blend, though the labels are often used interchangeably. In my usage, portmanteaus are originally deliberate creations, often devised with playful intent, while blends are inadvertent errors. You’re under no obligation to follow my usage, of course.)
Phrasal overlap portmanteaus (POPs for short) don’t have to be based on two-word expressions exclusively. “Pop goes the weasel words” would be entirely possible, and more elaborate POPs than this are attested — in particular, the wonderful “I’ll kick him in the Ball’s Pond Road”, from the Monty Python Word Association Football — note the POP — routine on the Matching Tie and Handkerchief album. This has overlapping kick him in the balls (from a partially open idiom family, or small construction, V SOMEONE in the BODY-PART) and the proper noun Ball’s Pond Road (the name of a London street).
[Entertaining digression: People trying to transcribe the Python routine who don't catch the London street reference cope as best they can with what they hear: for instance, "kick him in the balls upon the road" (possibly just a phonological reinterpretation) and "kick him in the balls down the road" (a rationalization of the expression that treats it as a syntactic portmanteau, but of a more routine type: "kick him in the balls" + "kick him down the road").]
We’ve been on to POPs before, notably in a Language Log posting of mine, “Sweet Tooth Fairies”, reporting on Erin McKean’s longer, and delightful, discussion in a Boston Globe “The Word” column. And then I returned to the topic on this blog, on “dilating eye teeth”, here; this one’s a combo of the VP dilating [one's] eye and the (opaque) N + N compound eye teeth.
I suppose that phrasal-overlap combos occasionally arise as inadvertent blends, but mostly they’re playful deliberate portmanteaus. People invent them as a game, playing (figuratively) for cleverness points.