• by Karlene Lukovitz  @KLmarketdaily, February 28, 2011

McDonald's is employing a cause-related promotion on Foursquare to promote its new McCafe Shake, while Dunkin' Donuts is running a Twitter-based giveaway to promote a new Big 'N Toasty Breakfast Sandwich.

McDonald's official launch of the McCafe Shake -- its classic chocolate, vanilla and strawberry shakes served in a clear McCafe cup and topped with whipped cream and a cherry -- is being tied in with a McCafe Shake "Social Fundraiser" between March 1 and 17.

During that period, each time a customer checks in on Foursquare at any McD's restaurant in the Philadelphia region and sends the check-in to Twitter with an @McDPhilly mention, the chain will donate $1 to Ronald McDonald House Charities (RMHC). All consumers participating in the social fundraiser will also receive a coupon for a free McCafe Shake.

In addition, McDonald's will feature its Shamrock Shake between March 1 and 31, and will donate a portion of each of those shake sales to RMHC.

At Dunkin', the new, limited-time Big 'N Toasty offering -- a heartier breakfast sandwich featuring two fried eggs, four slices of bacon and a slice of cheese on two thick slices of Texas toast (priced at $3.29) -- is being promoted with "Big 'N Toasty Trivia Tuesdays."

On all five Tuesdays during March, Twitter followers of Dunkin' (@DunkinDonuts) can watch for two questions posed by the chain that relate to "some of the world's biggest things." Those who tweet correct answers using a hashtag (#BigNToasty) will be eligible for a chance to win a $100 Dunkin' card. Dunkin' will award a total of 10 of the $100 cards (one for each trivia question) throughout the month.