The ornamental design for a magnetic garterbelt, as shown and described.
FIG. 1 is a front elevational view of the claimed magnetic garter belt;
FIG. 2 is an enlarged exploded perspective view thereof;
FIG. 3 is an enlarged perspective view thereof;
FIG. 4 is an enlarged front elevation view thereof;
FIG. 5 is an enlarged back elevation view thereof;
FIG. 6 is an enlarged left side elevation view thereof;
FIG. 7 is an enlarged bottom plan view thereof; and,
FIG. 8 is an enlarged top plan view thereof.
The partial human figure illustrated by broken lines depicts how the claimed design may appear when worn and forms no part of the claimed design. The features of the article of manufacture illustrated by broken lines represent environmental subject matter that forms no part of the claimed design.