The ornamental design for the shower hook assembly, as shown and described.
FIG. 1 is a front elevational view of my design;
FIG. 2 is a right side elevational view of my design;
FIG. 3 is a left side elevational view of my design;
FIG. 4 is a bottom elevational view of my design;
FIG. 5 is a top elevational view of my design;
FIG. 6 is a top front right perspective view of my design, illustrating the environment of intended use of my design, wherein the dotted lines indicate an exemplary bathing environment and is not a part of my claimed design; and,
FIG. 7 is a top front right perspective view of my design, illustrating intended use in its environment wherein the dotted lines indicating an exemplary bathing environment and is not a part of my claimed design.
The broken lines in the drawings depict environmental subject matter only and form no part of the claimed design.