stiff arm [stif ahrm]
1. When a tandem nursing twin baby places his or her inward facing arm such that the elbow is not bent and then pushes away his or her sibling forcefully.
Warning, a stiff arm may result in the following:
- spilled milk
- scratched faces
- uncontrollable laughter
- distracted babies
Nathan has gotten to where he will hold Anthony’s arm down by his wrist so Anthony can’t stiff arm him while they eat together.