Have a 2-hour layover at LGA...Where can I get bagel & black + white cookie HOOK-UP?
Well LGA is not exactly situated in prime Bagel OR B&W territory. If it were me, I'd probably take the M60 bus to the Jackson Hole, which is on Astoria Blvd. right around 49th st (it could be on 70-somethingth street, because the streets jump from the 70s straight to the 40s there). It's a great old-timey diner, probably has decent bagels (but not b&ws) and it's REALLY close to LaGuardia (about 5 minutes, once you're out of the airport).
If you are desperate: Natale bakery on Steinway Street near 28th ave. in Astoria makes decent black and whites. You would take the M60 and get off at Steinway street - then you'd get out, walk over the grand central parkway on steinway, and cross 25th and 28th aves. It'll be there on your left. But this is 10 minutes out of LGA and another 10 minutes walking time, and who knows how long it'll take the M60 to get out of the airport (or show up). If you're cabbing it that's another story.
Brooklyn Bagels, in Astoria at 35th St. and Broadway are quite good - but you can only do it if you're cabbing it. There are probably some okay black and whites nearby, but someone else will have to tell you where.
There are also some bagel joints, I think, in the Ditmars area - but I'm not sure which/where.