folding along line 18 may be promoted by an opening such as mouth area 22 along the line and or the head may have a relatively thin wall along the line that part of the head which is below fold line 18 inverts or folds upwardly into the interior of the top part of the head above the fold line the collapsed head may bulge slightly outwardly around line 18 as designated at 20 in fig4 imparting a bell shape to the part of the head above line 18 as shown in fig3 and 4 restraining means is provided to hold upper portion in collapsed position with respect to the lower portion the restraining means may take various forms in the embodiment of fig1 4 the restraining means comprises an interconnectable friction plug 26 28 plug half 26 is a downwardly opening cup positioned on the inside of the head at the top while the other plug half 28 is an upstanding post inside the head at the top of the neck 16 of the body these are preferably molded integrally on the respective portions 12 14 upper plug half 26 interfits frictionally with the lower half 28 when they are brought together to hold.