Lyndon Johnson actually said...
In computing the incentive pay of members of a submarine operational command staff under this subsection (1) for fractions of a calendar month, the time required to be served during underway operations shall bear the same ratio to the time required for a full calendar month as the period in question bears to a full calendar month
Context
Executive Order 11253—Amending Executive Order No. 11157 as it Relates to Incentive Pay for Hazardous Duty
10/19/1965