My fiancee and I gave a new bride and groom a brand new enema kit, for marital health (in all dimensions).
When we visited their new home a week later, they suggested we had "also" given them a gag gift -- their best man had pulled a prank on them -- but we told them that it was deadly serious, given in the spirit of helping them have good health, and given in the spirit of helping them have "other benefits."