The little lady mentioned this strange new piece of technology the other day. It's called a nursing tank. Apparently, when military humvees run low on fuel, nursing tanks roll on up and let them top off.
There are several problems with nursing tanks. First of all, their enlarged guns tend to wear on the turret mounting. The tank's main operator needs to be very careful with them, and should generally avoid frivolous use. This is usually very disappointing to tank drivers.
Secondly, humvees are not very gentle when refueling. If the nozzles don't fit perfectly, they tend to wear away at the tip of the nursing tank's nozzle. This is extremely wearing on the nursing tank, and the tank driver gets a lot of complaints about nozzle fatigue.
Finally, there's the issue of leakage. Nozzle pressure has to vary from the not infrequent and occasionally unpredictable refueling schedules of little humvees. This can wear on the seals and the pressure of the nursing tanks reservoirs, resulting in occasional leakage. Not only is this conspicuous for the nursing tank, but it also confuses tank drivers.
Nursing tanks. A neat idea with several associated problems.
At least, that's what I think the wife was talking about.