Pop-up sprinkler
FIG. 1 is a top perspective view of a pop-up sprinkler showing my new design; 
     FIG. 2 is an elevational view taken from the top side of FIG. 3. 
     FIG. 3 is a top plan view thereof; 
     FIG. 4 is an elevational view taken from the left side of FIG. 3. 
     FIG. 5 is a bottom plan view thereof; and 
     FIG. 6 is a top perspective view thereof with the pop-up sprinkler shown in the extended position. 
     The broken-line showing of the sprinkler head is for illustrative purposes only and forms no part of the claimed design.