Trampoline payments are a proposed type of payment where the spender routes the payment to an intermediate node who can select the rest of the path to the final receiver.
Using a single trampoline node necessarily reveals the destination to it. To regain privacy, a spender may require a payment be routed through multiple trampoline nodes so that none of them knows whether they’re routing the payment to the final receiver or just another intermediate trampoline node.
Although allowing trampoline nodes to select part of the path likely requires paying more routing fees, it means the spender doesn’t need to know how to route payments to any arbitrary node—it’s sufficient for the spender to know how to route a payment to any trampoline-compatible node. This is advantageous for lightweight LN clients that aren’t able to track the full network graph because they’re often offline or run on underpowered mobile hardware.