Learn this one simple trick to forcibly increase any smart contract's balance!
This repo contains a small utility contract written in Solidity and EVM assembly that sends ether to other addresses by means of SUICIDE/SELFDESTRUCT. Unlike for a normal send/call, if the receiving address belongs to a contract, the contract's code is never called; one can forcibly increase any contract's balance!
If you're interested in the implications of this trick, I recommend looking at João Carvalho's and Richard Moore's entries to the first Underhanded Solidity Contest. Anybody writing smart contracts should be aware of forced balance increases lest their contracts be vulnerable.
The contract is deployed on the Ethereum mainnet at address 0xE7850f1A4d21bBd2f819374457C83A6fF84E70d3.