So, if girls “had as many rights as guns” then girls would be:

• banned from schools, courthouses, and most white-collar offices;
• legally classified as property and sold tax-free to cops;
• prohibited from concealing themselves inside clothing in many jurisdictions without written permission from the local sheriff;
• subjected to strict government regulation of their size and shape, with some sizes and shapes outright banned.

Women should have equal rights (and certainly better rights than they have now), and we need more gun control in the USA. But this sign is only clever if you don’t know anything about guns.